Paroxysmal Nocturnal Hemoglobinuria

Overview

Epidemiology

• Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency: approximately 5 cases per million patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
• Sex Sex The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the male from the female organism. Gender Dysphoria ratio: men = women
• Ages affected: mostly young adults; also children and those > 70 years

Etiology

• X-linked X-linked Genetic diseases that are linked to gene mutations on the X chromosome in humans or the X chromosome in other species. Included here are animal models of human X-linked diseases. Common Variable Immunodeficiency (CVID) somatic mutation Somatic Mutation Non-Hodgkin Lymphomas of the phosphatidylinositol N-acetylglucosaminyltransferase subunit A (PIG-A) gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics in a multipotent hematopoietic stem cell 
• PIG-A gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics: responsible for the 1st step in synthesis Synthesis Polymerase Chain Reaction (PCR) of glycosylphosphatidylinositol (GPI) 
• GPI anchors dozens of proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis to the cell surface, including complement inhibitors (regulators) CD59 and CD55.
• CD59: protects RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology against membrane attack complex Membrane attack complex A product of complement activation cascade, regardless of the pathways, that forms transmembrane channels causing disruption of the target cell membrane and cell lysis. It is formed by the sequential assembly of terminal complement components (complement C5b; complement C6; complement C7; complement C8; and complement C9) into the target membrane. The resultant C5b-8-poly-c9 is the ‘membrane attack complex’ or MAC. Type II Hypersensitivity Reaction (MAC)–mediated intravascular hemolysis Intravascular hemolysis Hemolytic Anemia
• CD55: protects RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology against opsonization by complement C3b Complement C3b The larger fragment generated from the cleavage of complement C3 by C3 convertase. It is a constituent of the alternative pathway C3 convertase (c3bbb), and complement C5 convertases in both the classical (c4b2a3b) and the alternative (c3bbb3b) pathway. C3b participates in immune adherence reaction and enhances phagocytosis. It can be inactivated (ic3b) or cleaved by various proteases to yield fragments such as complement C3c; complement C3d; C3e; C3f; and C3g. C3 Deficiency and subsequent extravascular hemolysis Extravascular hemolysis Hemolytic Anemia
• RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology may show partial or complete absence of GPI-anchored proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis (APs).
• Benign Benign Fibroadenoma clonal expansion Clonal Expansion Seborrheic Keratosis of the mutated stem cells gives rise to CD59/CD55-deficient RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology. 

Classification

Classic paroxysmal nocturnal hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions (PNH): 

• Clinical evidence of intravascular hemolysis Intravascular hemolysis Hemolytic Anemia: 
  • Reticulocytosis
  • ↑ Serum LDH LDH Osteosarcoma 
  • ↑ Indirect bilirubin Indirect Bilirubin Liver Function Tests
  • Low serum haptoglobin
• No evidence of a preexisting defined bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis abnormality

PNH in the setting of a specified bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis disorder: 

• Clinical and laboratory evidence of hemolysis
• Comorbid preexisting defined marrow abnormality (or history of one): 
  • Aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia
  • Myelodysplastic syndrome
  • Myelofibrosis

Subclinical PNH (PNH-sc): 

• Comorbid preexisting defined marrow abnormality (or a history of one): 
  • Aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia
  • Myelodysplastic syndrome
  • Myelofibrosis
• Small populations of GPI-AP–deficient erythrocytes Erythrocytes Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology and/or granulocytes Granulocytes Leukocytes with abundant granules in the cytoplasm. They are divided into three groups according to the staining properties of the granules: neutrophilic, eosinophilic, and basophilic. Mature granulocytes are the neutrophils; eosinophils; and basophils. White Myeloid Cells: Histology detected by flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure cytometric analysis 
• No clinical or laboratory evidence of hemolysis

Pathophysiology

Genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics

PIG-A gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics (normal physiology):

• Located on the X chromosome X chromosome The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species. Basic Terms of Genetics 
• Codes for GPI:
  • Anchors certain proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis to cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane
  • Anchors CD55 and CD 59 in multiple blood cell lines: 
    • Erythrocytes Erythrocytes Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology
    • Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation
    • Monocytes Monocytes Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles. Innate Immunity: Phagocytes and Antigen Presentation
    • Platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology
  • CD55 and CD59 are complement-regulating surface proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis:
    • Prevent binding of complement to circulating blood cells
    • CD59 (also called membrane inhibitor of reactive lysis (MIRL)) prevents formation of MAC (prevents intravascular hemolysis Intravascular hemolysis Hemolytic Anemia).
    • CD55 (also called decay accelerating factor) prevents opsonization/complement-mediated blood cell destruction in the spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy (prevents extravascular hemolysis Extravascular hemolysis Hemolytic Anemia).

PIG-A gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics ( mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations):

• Mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations of hematopoietic progenitor cells 
• Results in clonal expansion Clonal Expansion Seborrheic Keratosis of multiple blood cell lines:
  • Erythrocytes Erythrocytes Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology
  • Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation
  • Monocytes Monocytes Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles. Innate Immunity: Phagocytes and Antigen Presentation
  • Platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology
• Blood cells lack surface proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis CD55 and CD59:
  • Uncontrolled amplification of complement system Complement system Serum glycoproteins participating in the host defense mechanism of complement activation that creates the complement membrane attack complex. Included are glycoproteins in the various pathways of complement activation (classical complement pathway; alternative complement pathway; and lectin complement pathway). Innate Immunity: Barriers, Complement, and Cytokines
  • Intravascular and extravascular hemolysis Extravascular hemolysis Hemolytic Anemia ensue.
  • Multiple downstream pathologic manifestations

Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis failure

• Defined as peripheral cytopenias Cytopenias IPEX Syndrome associated with deficient hematopoiesis Hematopoiesis The development and formation of various types of blood cells. Hematopoiesis can take place in the bone marrow (medullary) or outside the bone marrow (extramedullary hematopoiesis). Bone Marrow: Composition and Hematopoiesis
• Present, to some degree, in all patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with PNH
• Unknown mechanism of association between PNH and aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia ( AA AA Amyloidosis):
  • Aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia develops in 10%–20% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with PNH.
  • Paroxysmal nocturnal hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions develops in 5% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with AA AA Amyloidosis.
• Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis failure in PNH is highly variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables: 
  • Mild decrease in hematopoietic stem cells Hematopoietic stem cells Progenitor cells from which all blood cells derived. They are found primarily in the bone marrow and also in small numbers in the peripheral blood. Bone Marrow: Composition and Hematopoiesis (mild end of spectrum) 
  • Severe AA AA Amyloidosis (severe end of spectrum)
• Mechanism of bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis failure in PNH:
  • Proposed mechanism is complement-mediated destruction of hematopoietic precursor cells.
  • Still poorly understood

Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types

• Primary mechanism is intravascular hemolysis Intravascular hemolysis Hemolytic Anemia:
  • Circulating RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology lack the protective effect of CD59
  • Complement factors assemble/activate MAC on RBC membrane and lyse the cell:
    • Hemoglobin released into circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
    • Multiple downstream pathologic manifestations
• Secondary mechanism is extravascular hemolysis Extravascular hemolysis Hemolytic Anemia:
  • Circulating RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology lack the protective effect of CD55.
  • Complement opsonizes or accumulates on red cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane.
  • Opsonization marks red cells for phagocytic clearance in the spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy.
• Other factors contributing to anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types:
  • Iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements loss from excessive and chronic red cell lysis:
    • Some iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements lost to hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions
    • Some iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements lost to tissue deposition
  • Lack of erythrocyte production:
    • Underlying bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis failure
    • Iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements deficiency

Neutrophil involvement

Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation also exhibit deficiency of GPI-APs:

• Increased sensitivity to complement-mediated lysis
• Once lysed, may release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology cytokines Cytokines Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner. Adaptive Immune Response into circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment:
  • Further accelerate complement activity
  • Increased thrombogenic potential
• Excessive neutrophil lysis may lead to increased susceptibility to infection.

Platelet involvement

Platelet-mediated factors include:

• Nitrous oxide Nitrous oxide Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. Inhaled Anesthetics (NO) deficiency leads to platelet activation Platelet activation A series of progressive, overlapping events, triggered by exposure of the platelets to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable hemostatic plug. Hemostasis and aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies.
• Platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology deficient in GPI-linked proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis become activated by complement.
• Lack of CD59 on platelet membranes induces platelet aggregation Platelet aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Hemostasis in particular.

Thrombophilia Thrombophilia A disorder of hemostasis in which there is a tendency for the occurrence of thrombosis. Hypercoagulable States and thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus

Thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus in unusual sites (hepatic, mesenteric, cerebral, dermal veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology) is typical of PNH.

• NO-mediated factors: 
  • On red cell lysis, hemoglobin released into the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
  • Hemoglobin is bound to haptoglobin until haptoglobin is saturated.
  • After saturating haptoglobin, free hemoglobin binds to circulating NO, which:
    • Normally decreases endothelial adhesion Adhesion The process whereby platelets adhere to something other than platelets, e.g., collagen; basement membrane; microfibrils; or other ‘foreign’ surfaces. Coagulation Studies
    • Normally prevents platelet activation Platelet activation A series of progressive, overlapping events, triggered by exposure of the platelets to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable hemostatic plug. Hemostasis and aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies
    • Normally causes vasodilation Vasodilation The physiological widening of blood vessels by relaxing the underlying vascular smooth muscle. Pulmonary Hypertension Drugs
  • But if NO is depleted in the peripheral circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment:
    • ↓ NO enhances endothelial adhesion Adhesion The process whereby platelets adhere to something other than platelets, e.g., collagen; basement membrane; microfibrils; or other ‘foreign’ surfaces. Coagulation Studies.
    • ↓ NO enhances platelet activation Platelet activation A series of progressive, overlapping events, triggered by exposure of the platelets to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable hemostatic plug. Hemostasis and aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies.
    • ↓ NO causes vasoconstriction Vasoconstriction The physiological narrowing of blood vessels by contraction of the vascular smooth muscle. Vascular Resistance, Flow, and Mean Arterial Pressure → exposure of tissue factor → triggers Triggers Hereditary Angioedema (C1 Esterase Inhibitor Deficiency) the extrinsic coagulation cascade Coagulation cascade The coagulation cascade is a series of reactions that ultimately generates a strong, cross-linked fibrin clot. Hemostasis.
• Platelet-mediated factors:
  • NO deficiency leads to platelet activation Platelet activation A series of progressive, overlapping events, triggered by exposure of the platelets to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable hemostatic plug. Hemostasis and aggregation Aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Coagulation Studies.
  • Platelets Platelets Platelets are small cell fragments involved in hemostasis. Thrombopoiesis takes place primarily in the bone marrow through a series of cell differentiation and is influenced by several cytokines. Platelets are formed after fragmentation of the megakaryocyte cytoplasm. Platelets: Histology deficient in GPI-linked proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis become activated by complement.
  • Lack of CD59 on platelet membranes induces platelet aggregation Platelet aggregation The attachment of platelets to one another. This clumping together can be induced by a number of agents (e.g., thrombin; collagen) and is part of the mechanism leading to the formation of a thrombus. Hemostasis.
• Vascular factors:
  • Activation of complement on endothelial cell surfaces
  • Intravascular hemolysis Intravascular hemolysis Hemolytic Anemia may provide friable membrane surfaces on which coagulation may be initiated.
  • Slow flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure: PNH thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus is far more common in the venous than in the arterial system, notably in large veins Large veins Veins: Histology or where flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure is slowest.
    • Hepatic
    • Portal
    • Splenic
    • Mesenteric
    • Pulmonary
    • Cerebral
    • Dermal
• Other factors:
  • Unknown mechanism of increased procoagulant and fibrinolytic activity
  • White cell lysis may release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology vasoactive and/or thrombogenic molecules.

Renal involvement

Renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome is progressive and multifactorial.

• Acute tubular necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage effects of heme and iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements (pigment nephropathy)
• Tubular obstruction with pigment casts
• Decreased renal perfusion from renal vein Renal vein Short thick veins which return blood from the kidneys to the vena cava. Glomerular Filtration thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus
• Decreased renal perfusion from arterial thrombosis Arterial Thrombosis Hypercoagulable States
• Decreased renal perfusion from ↓ NO-mediated vasoconstriction Vasoconstriction The physiological narrowing of blood vessels by contraction of the vascular smooth muscle. Vascular Resistance, Flow, and Mean Arterial Pressure

Smooth muscle dystonia Dystonia Dystonia is a hyperkinetic movement disorder characterized by the involuntary contraction of muscles, resulting in abnormal postures or twisting and repetitive movements. Dystonia can present in various ways as may affect many different skeletal muscle groups. Dystonia

• Upon red cell lysis, hemoglobin released into the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
• Hemoglobin is bound to haptoglobin until haptoglobin is saturated.
• After saturating haptoglobin, free hemoglobin binds to circulating NO, which:
  • Normally relaxes smooth muscle tone Muscle tone The state of activity or tension of a muscle beyond that related to its physical properties, that is, its active resistance to stretch. In skeletal muscle, tonus is dependent upon efferent innervation. Skeletal Muscle Contraction
  • Is depleted in the peripheral circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
• NO depletion leads to smooth muscle contraction Smooth muscle contraction Smooth muscle is primarily found in the walls of hollow structures and some visceral organs, including the walls of the vasculature, GI, respiratory, and genitourinary tracts. Smooth muscle contracts more slowly and is regulated differently than skeletal muscle. Smooth muscle can be stimulated by nerve impulses, hormones, metabolic factors (like pH, CO2 or O2 levels), its own intrinsic pacemaker ability, or even mechanical stretch. Smooth Muscle Contraction.
• Clinical manifestations depend on the smooth muscle population affected.

Paroxysms of hemolysis

Exacerbations of hemolysis may be due to:

• Administration of iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements to an iron-deficient patient: 
  • Erythrocytes Erythrocytes Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology lacking CD59/CD55 released into circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
  • Intravascular/ extravascular hemolysis Extravascular hemolysis Hemolytic Anemia ensues
• Exogenous activation of the complement system Complement system Serum glycoproteins participating in the host defense mechanism of complement activation that creates the complement membrane attack complex. Included are glycoproteins in the various pathways of complement activation (classical complement pathway; alternative complement pathway; and lectin complement pathway). Innate Immunity: Barriers, Complement, and Cytokines:
  • Infection/ sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock
  • Surgery/trauma
  • Drugs

Antibody involvement

• Coombs testing detects the presence of antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions in autoimmune hemolytic anemias.
• Untreated PNH is a Coombs-negative hemolytic anemia Hemolytic Anemia Hemolytic anemia (HA) is the term given to a large group of anemias that are caused by the premature destruction/hemolysis of circulating red blood cells (RBCs). Hemolysis can occur within (intravascular hemolysis) or outside the blood vessels (extravascular hemolysis). Hemolytic Anemia.
• Coombs-positivity often occurs in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with PNH treated with eculizumab:
  • Eculizumab is a monoclonal antibody that blocks complement-mediated formation of MAC:
    • Intravascular hemolysis Intravascular hemolysis Hemolytic Anemia does not occur.
    • This antibody is detected by the Coombs test.
  • Complement factors not consumed by MAC formation are free in the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment and coat red cell surfaces lacking protection from CD55:
    • RBC is now opsonized by complement.
    • Opsonized RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology undergo extravascular hemolysis Extravascular hemolysis Hemolytic Anemia.

Clinical Presentation

Hemolysis-associated symptoms

• Hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions:
  • Classically noticed at 1st morning void
  • Can occur at any time of day or night
  • Intermittent (paroxysmal) in nature
• Jaundice Jaundice Jaundice is the abnormal yellowing of the skin and/or sclera caused by the accumulation of bilirubin. Hyperbilirubinemia is caused by either an increase in bilirubin production or a decrease in the hepatic uptake, conjugation, or excretion of bilirubin. Jaundice/ icterus Icterus A clinical manifestation of hyperbilirubinemia, characterized by the yellowish staining of the skin, mucous membranes, and sclera. Clinical jaundice usually is a sign of liver dysfunction. Jaundice
• Heme/iron-related nephrotoxicity Nephrotoxicity Glycopeptides:
  • Acute renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome
  • Chronic renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome

Anemia-associated symptoms

• Fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia
• Weakness
• Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
• Palpitations Palpitations Ebstein’s Anomaly
• Pallor
• Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children

Smooth muscle contraction Smooth muscle contraction Smooth muscle is primarily found in the walls of hollow structures and some visceral organs, including the walls of the vasculature, GI, respiratory, and genitourinary tracts. Smooth muscle contracts more slowly and is regulated differently than skeletal muscle. Smooth muscle can be stimulated by nerve impulses, hormones, metabolic factors (like pH, CO2 or O2 levels), its own intrinsic pacemaker ability, or even mechanical stretch. Smooth Muscle Contraction–associated symptoms

These symptoms are due to decreased circulating NO:

• Dysphagia Dysphagia Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Dysphagia (esophageal)
• Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics (intestinal)
• Abdominal pain Abdominal Pain Acute Abdomen (intestinal)
• Erectile dysfunction Erectile Dysfunction Erectile dysfunction (ED) is defined as the inability to achieve or maintain a penile erection, resulting in difficulty to perform penetrative sexual intercourse. Local penile factors and systemic diseases, including diabetes, cardiac disease, and neurological disorders, can cause ED. Erectile Dysfunction (microvascular/corpus cavernosa)
• Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension (pulmonary arterial)

Thrombosis-associated symptoms

• Limb edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema/discoloration/ pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways from deep vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus ( DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis)
• Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism
• Cerebral vein/dural vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus leads to:
  • Focal neurologic deficit Focal Neurologic Deficit Intracerebral Hemorrhage
  • Intracranial hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • Encephalopathy Encephalopathy Hyper-IgM Syndrome
• Dermal vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus leads to:
  • Bruising 
  • Purpura fulminans Purpura fulminans A severe, rapidly fatal reaction occurring most commonly in children following an infectious illness. It is characterized by large, rapidly spreading skin hemorrhages, fever, or shock. Purpura fulminans often accompanies or is triggered by disseminated intravascular coagulation. Disseminated Intravascular Coagulation
• Hepatic/portal/mesenteric vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus leads to:
  • Abdominal pain Abdominal Pain Acute Abdomen
  • Splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly
  • Budd-Chiari syndrome Budd-Chiari syndrome Budd-Chiari syndrome is a condition resulting from the interruption of the normal outflow of blood from the liver. The primary type arises from a venous process (affecting the hepatic veins or inferior vena cava) such as thrombosis, but can also be from a lesion compressing or invading the veins (secondary type). The patient typically presents with hepatomegaly, ascites, and abdominal discomfort. Budd-Chiari Syndrome

Neutropenia-associated symptoms

• Susceptibility to infection
• Increased circulating cytokines Cytokines Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner. Adaptive Immune Response leads to: 
  • Malaise Malaise Tick-borne Encephalitis Virus/ fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia
  • Inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation
  • Sepsis-like syndrome

Diagnosis

CBC

• Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types (↓ RBC count, ↓ hematocrit Hematocrit The volume of packed red blood cells in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, anemia shows a low value; polycythemia, a high value. Neonatal Polycythemia):
  • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables, but generally present to some degree
  • May be subtle or pronounced depending on degree of hemolysis
  • May or may not be normocytic, microcytic, or macrocytic depending on degree of vitamin B₁₂, folate Folate Folate and vitamin B12 are 2 of the most clinically important water-soluble vitamins. Deficiencies can present with megaloblastic anemia, GI symptoms, neuropsychiatric symptoms, and adverse pregnancy complications, including neural tube defects. Folate and Vitamin B12, or iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements deficiency
• ↓ or normal neutrophil count
• ↓ or normal platelet count
• ↑ Free hemoglobin

Chemistry

• ↑ AST AST Enzymes of the transferase class that catalyze the conversion of l-aspartate and 2-ketoglutarate to oxaloacetate and l-glutamate. Liver Function Tests/ ALT ALT An enzyme that catalyzes the conversion of l-alanine and 2-oxoglutarate to pyruvate and l-glutamate. Liver Function Tests (if hepatic congestion)
• ↑ Creatinine (if renal toxicity Toxicity Dosage Calculation)
• ↑ Bilirubin Bilirubin A bile pigment that is a degradation product of heme. Heme Metabolism 
• ↑ LDH LDH Osteosarcoma
• ↓ Leukocyte alkaline phosphatase Alkaline Phosphatase An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. Osteosarcoma (LAP)

Urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children

• Gross red or pink discoloration
• Positive for hemoglobin
• No RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology on microscopy
• +/– protein depending on renal integrity

Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis analysis

• GPI-AP deficiency can be demonstrated on bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis cells using flow cytometry Flow cytometry Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake. X-linked Agammaglobulinemia.
• Unnecessary for standard diagnosis of PNH
• Needed for proper classification:
  • Evaluate for other marrow failure syndromes.
  • Evaluate for other clonal myelopathies.

Flow cytometry Flow cytometry Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake. X-linked Agammaglobulinemia (FCM) performed on peripheral blood

• Indicated for screening Screening Preoperative Care for:
  • Hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions
  • Coombs-negative intravascular hemolysis Intravascular hemolysis Hemolytic Anemia 
  • Abnormally high serum LDH LDH Osteosarcoma, especially with concurrent iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements deficiency
  • Venous thrombosis Venous thrombosis The formation or presence of a blood clot (thrombus) within a vein. Budd-Chiari Syndrome involving unusual sites
  • AA AA Amyloidosis (at diagnosis and once yearly)
  • Refractory anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
  • Myelodysplastic syndrome
  • Episodic dysphagia Dysphagia Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Dysphagia or abdominal pain Abdominal Pain Acute Abdomen with evidence of intravascular hemolysis Intravascular hemolysis Hemolytic Anemia
• Indicated for definitive diagnosis and monitoring of PNH:
  • Must show ≥ 5% population of RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology that are deficient in CD55 and CD59 or ≥ 20% of CD55/CD59-deficient granulocytes Granulocytes Leukocytes with abundant granules in the cytoplasm. They are divided into three groups according to the staining properties of the granules: neutrophilic, eosinophilic, and basophilic. Mature granulocytes are the neutrophils; eosinophils; and basophils. White Myeloid Cells: Histology to be diagnostic for PNH.
  • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with proven GPI-AP deficiency should be monitored yearly to track size of clonal population.

Management

Medical management

• Eculizumab or ravulizumab: humanized monoclonal antibodies Monoclonal antibodies Antibodies produced by a single clone of cells. Ebolavirus and Marburgvirus that bind BIND Hyperbilirubinemia of the Newborn to the complement component C5
• Prevents cleavage of C5 and intravascular hemolysis Intravascular hemolysis Hemolytic Anemia by MACs 
• Effect:
  • Elimination Elimination The initial damage and destruction of tumor cells by innate and adaptive immunity. Completion of the phase means no cancer growth. Cancer Immunotherapy or marked reduction in blood transfusions Blood transfusions The introduction of whole blood or blood component directly into the bloodstream. Transfusion Products 
  • Marked decrease in thrombotic complications
• Administration: 
  • IV every 2 weeks for eculizumab 
  • IV every 8 weeks for ravulizumab 
• Disadvantages:
  • Increased risk of life-threatening Neisseria Neisseria Neisseria is a genus of bacteria commonly present on mucosal surfaces. Several species exist, but only 2 are pathogenic to humans: N. gonorrhoeae and N. meningitidis. Neisseria species are non-motile, gram-negative diplococci most commonly isolated on modified Thayer-Martin (MTM) agar. Neisseria infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, requiring pretreatment vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination and daily antibiotics for prophylaxis Prophylaxis Cephalosporins
  • High cost: approximately $400,000 (U.S.)/year
• Extravascular hemolysis Extravascular hemolysis Hemolytic Anemia will still continue, owing to opsonization of RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology by C3 fragments.

Bone marrow transplantation Bone marrow transplantation Transfer of hematopoietic stem cells from bone marrow or blood between individuals within the same species (homologous transplantation) or transfer within the same individual (autologous transplantation). Hematopoietic stem cell transplantation has been used as an alternative to bone marrow transplantation in the treatment of a variety of neoplasms. Organ Transplantation

• The only definitive cure, but has substantial intrinsic risks
• Indicated mostly for: 
  • Severe AA AA Amyloidosis
  • Severe myelodysplastic syndrome
  • PNH complications unresponsive to complement inhibitors (or if they are not available)

Supportive care

• Always provided regardless of other therapies provided
• RBC transfusions of leukocyte-reduced/filtered blood (used now routinely for all transfused blood): 
  • Decreases risk of antibody reaction to leukocyte antigens
  • Decreases complement activation Complement Activation The sequential activation of serum complement proteins to create the complement membrane attack complex. Factors initiating complement activation include antigen-antibody complexes, microbial antigens, or cell surface polysaccharides. Systemic Lupus Erythematosus
• Vitamin B₁₂/folic acid supplementation if ongoing hemolysis
• Iron supplementation Iron Supplementation Iron Deficiency Anemia if iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements deficient owing to hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions
• Anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with history of or genetic predisposition to thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus: lifelong anticoagulation Anticoagulation Pulmonary Hypertension Drugs if high risk or if atypical thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus has occurred
• Regular Regular Insulin monitoring (every 6–12 months): 
  • CBC/DIFF
  • Reticulocyte Reticulocyte Immature erythrocytes. In humans, these are erythroid cells that have just undergone extrusion of their cell nucleus. They still contain some organelles that gradually decrease in number as the cells mature. Ribosomes are last to disappear. Certain staining techniques cause components of the ribosomes to precipitate into characteristic ‘reticulum’ (not the same as the endoplasmic reticulum), hence the name reticulocytes. Erythrocytes: Histology count
  • LDH LDH Osteosarcoma
  • Chemistry profile ( electrolytes Electrolytes Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions. Electrolytes, renal function, hepatic function)
  • Iron studies Iron Studies Iron Deficiency Anemia (serum iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements, total iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements binding capacity, and ferritin Ferritin Iron-containing proteins that are widely distributed in animals, plants, and microorganisms. Their major function is to store iron in a nontoxic bioavailable form. Each ferritin molecule consists of ferric iron in a hollow protein shell (apoferritins) made of 24 subunits of various sequences depending on the species and tissue types. Hereditary Hemochromatosis)
  • FCM to determine any change in PNH clone size
  • Bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma if pancytopenia Pancytopenia Deficiency of all three cell elements of the blood, erythrocytes, leukocytes and platelets. Aplastic Anemia or suspected AA AA Amyloidosis or myelodysplastic syndrome

Prognosis

• Natural history, with only supportive treatment given: 
  • Median survival after diagnosis: 10–20 years
  • Major complications: 
    • Pancytopenia Pancytopenia Deficiency of all three cell elements of the blood, erythrocytes, leukocytes and platelets. Aplastic Anemia 
    • Thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus
    • Myelodysplastic syndrome
  • Causes of death: 
    • Venous thrombosis Venous thrombosis The formation or presence of a blood clot (thrombus) within a vein. Budd-Chiari Syndrome: number-one cause
    • Infection if severe neutropenia Severe Neutropenia Neutropenia
    • AML AML Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the uncontrolled proliferation of myeloid precursor cells. Seen predominantly in older adults, AML includes an accumulation of myeloblasts and a replacement of normal marrow by malignant cells, which leads to impaired hematopoiesis. Acute Myeloid Leukemia
• With complement inhibitors (eculizumab and ravulizumab), mortality Mortality All deaths reported in a given population. Measures of Health Status appears similar to that for age-matched controls, but limited time data so far
• Bone marrow transplantation Bone marrow transplantation Transfer of hematopoietic stem cells from bone marrow or blood between individuals within the same species (homologous transplantation) or transfer within the same individual (autologous transplantation). Hematopoietic stem cell transplantation has been used as an alternative to bone marrow transplantation in the treatment of a variety of neoplasms. Organ Transplantation: curative but significant inherent risks involved
• Full, spontaneous recovery rarely occurs.

Differential Diagnosis

• Hemolytic anemia Hemolytic Anemia Hemolytic anemia (HA) is the term given to a large group of anemias that are caused by the premature destruction/hemolysis of circulating red blood cells (RBCs). Hemolysis can occur within (intravascular hemolysis) or outside the blood vessels (extravascular hemolysis). Hemolytic Anemia ( HA HA Hemolytic anemia (HA) is the term given to a large group of anemias that are caused by the premature destruction/hemolysis of circulating red blood cells (RBCs). Hemolysis can occur within (intravascular hemolysis) or outside the blood vessels (extravascular hemolysis). Hemolytic Anemia): hereditary disorders (e.g., glucose-6-phosphate dehydrogenase Glucose-6-phosphate dehydrogenase Pentose Phosphate Pathway ( G6PD G6PD Pentose Phosphate Pathway) deficiency, hereditary spherocytosis Hereditary Spherocytosis Hereditary spherocytosis (HS) is the most common type of hereditary hemolytic anemia. The condition is caused by a cytoskeletal protein deficiency in the RBC membrane. This results in loss of membrane stability and deformability of the RBC, giving the cell its spherical shape (spherocyte). Hereditary Spherocytosis, sickle cell anemia Sickle cell anemia A disease characterized by chronic hemolytic anemia, episodic painful crises, and pathologic involvement of many organs. It is the clinical expression of homozygosity for hemoglobin S. Sickle Cell Disease) or acquired disorders (e.g., immune disorders, toxic chemicals and drugs, antiviral Antiviral Antivirals for Hepatitis B agents, physical damage, infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease) that also present with hemolysis leading to anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types (but not with thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus and bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis failure). This is a broad category, as the hemolytic anemias each have a unique mechanism, presentation, and management. 
• Aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia ( AA AA Amyloidosis): occurs as a result of hematopoietic stem cell damage. More than 10% of AA AA Amyloidosis cases will develop into PNH. In addition, some people with PNH will develop AA AA Amyloidosis. Like PNH, AA AA Amyloidosis presents with bone marrow Bone marrow The soft tissue filling the cavities of bones. Bone marrow exists in two types, yellow and red. Yellow marrow is found in the large cavities of large bones and consists mostly of fat cells and a few primitive blood cells. Red marrow is a hematopoietic tissue and is the site of production of erythrocytes and granular leukocytes. Bone marrow is made up of a framework of connective tissue containing branching fibers with the frame being filled with marrow cells. Bone Marrow: Composition and Hematopoiesis failure and low blood cell counts (but not thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus). Treatment for AA AA Amyloidosis might include medications, blood transfusions Blood transfusions The introduction of whole blood or blood component directly into the bloodstream. Transfusion Products, or stem cell transplantation.
• Acute mesenteric ischemia Acute Mesenteric Ischemia Mesenteric Ischemia: presents with severe acute abdominal pain Abdominal Pain Acute Abdomen in a patient with an identifiable source of thrombus/emboli obstructing the mesenteric vessels (e.g., preexisting atheroma, atrial fibrillation Atrial fibrillation Atrial fibrillation (AF or Afib) is a supraventricular tachyarrhythmia and the most common kind of arrhythmia. It is caused by rapid, uncontrolled atrial contractions and uncoordinated ventricular responses. Atrial Fibrillation). Diagnosed with angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery. Treated with embolectomy or surgery to remove necrotic bowel. 
• Paroxysmal cold hemoglobinuria Hemoglobinuria The presence of free hemoglobin in the urine, indicating hemolysis of erythrocytes within the vascular system. After saturating the hemoglobin-binding proteins (haptoglobins), free hemoglobin begins to appear in the urine. Transfusion Reactions: rare autoimmune hemolytic anemia Autoimmune Hemolytic Anemia Autoimmune hemolytic anemia (AIHA) is a rare type of hemolytic anemia characterized by antibody production against self RBCs, leading to destruction of these cells in the spleen and other reticuloendothelial tissues. The disease is generally categorized as warm or cold, depending on the thermal reactivity of the autoantibodies. Autoimmune Hemolytic Anemia seen in young children, triggered by infectious disease, neoplasm, or immune dysfunction. IgM IgM A class of immunoglobulin bearing mu chains (immunoglobulin mu-chains). Igm can fix complement. The name comes from its high molecular weight and originally being called a macroglobulin. Immunoglobulins: Types and Functions antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions bind BIND Hyperbilirubinemia of the Newborn to the RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology in the cold and fix complement. Upon warming, the antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions dissociate and complement lyses the RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology, leading to extravascular hemolysis Extravascular hemolysis Hemolytic Anemia. Diagnosis is via Coombs testing. Treatment is preventive.
• Portal vein Portal vein A short thick vein formed by union of the superior mesenteric vein and the splenic vein. Liver: Anatomy obstruction: usually caused by primary thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus of the portal vein Portal vein A short thick vein formed by union of the superior mesenteric vein and the splenic vein. Liver: Anatomy due to an inherited or acquired coagulopathy or associated with cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis. Extrinsic obstruction also occurs. Correlative clinical findings raise clinical suspicion, but imaging (ultrasound or CT) showing a mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast or thrombus is diagnostic. Treatment includes thrombectomy Thrombectomy Surgical removal of an obstructing clot or foreign material from a blood vessel at the point of its formation. Removal of a clot arising from a distant site is called embolectomy. Vascular Surgery, excision of the mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast/ tumor Tumor Inflammation, and/or anticoagulation Anticoagulation Pulmonary Hypertension Drugs. 
• Renal vein Renal vein Short thick veins which return blood from the kidneys to the vena cava. Glomerular Filtration thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus: The most common cause of renal vein Renal vein Short thick veins which return blood from the kidneys to the vena cava. Glomerular Filtration thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus is nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome. Other causes include primary hypercoagulable Hypercoagulable Hypercoagulable states (also referred to as thrombophilias) are a group of hematologic diseases defined by an increased risk of clot formation (i.e., thrombosis) due to either an increase in procoagulants, a decrease in anticoagulants, or a decrease in fibrinolysis. Hypercoagulable States disorders (such as PNH), renal tumors, extrinsic compression Compression Blunt Chest Trauma, trauma, and, rarely, inflammatory bowel disease. This condition presents with renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome (acute or chronic). Diagnosed with imaging (ultrasound or CT). Treatment includes thrombectomy Thrombectomy Surgical removal of an obstructing clot or foreign material from a blood vessel at the point of its formation. Removal of a clot arising from a distant site is called embolectomy. Vascular Surgery, excision of the mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast/ tumor Tumor Inflammation, and/or anticoagulation Anticoagulation Pulmonary Hypertension Drugs.