Autoimmune Hemolytic Anemia

Overview

Definition

Autoimmune 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 (AIHA) is hemolysis or premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis destruction 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 due to autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques. There are 2 categories of AIHA based on the thermal reactivity of autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques:

• Warm AIHA
• Cold AIHA

Epidemiology

• 1–3 cases per 100,000 population per year
• Slightly more likely to occur in females than in males
• Secondary cause present in 20%–80% of reported cases
• Warm AIHA:
  • 70%–80% of AIHAs
  •  Seen in children 0–4 years old and in adults > 40 years old
• Cold AIHA: peak incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency in adults > 60 years old

Etiology

Warm AIHA:

• Idiopathic Idiopathic Dermatomyositis/primary: no underlying condition or medication 
• Secondary: associated with an underlying condition (50%–60% of cases)
  • Lymphoproliferative disorders Lymphoproliferative disorders Disorders characterized by proliferation of lymphoid tissue, general or unspecified. Lymphocytosis 
  • Autoimmune disorders 
  • Malignancy Malignancy Hemothorax
  • Immunodeficiency Immunodeficiency Chédiak-Higashi Syndrome
  • 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
  • Pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
  • Drugs 
  • Allogeneic hematopoietic stem cell transplantation Hematopoietic stem cell 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 (HSCT): usually 2–6 months after engraftment

Cold AIHA:

• Idiopathic Idiopathic Dermatomyositis/primary (cold agglutinin disease)
• Cold agglutinin syndrome:
  • Lymphoproliferative disorders Lymphoproliferative disorders Disorders characterized by proliferation of lymphoid tissue, general or unspecified. Lymphocytosis
  • 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
  • Autoimmune disease
  • Malignancy Malignancy Hemothorax 
• 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 (PCH) (seen almost exclusively in children):
  • Idiopathic Idiopathic Dermatomyositis
  • Secondary (can be acute transient or chronic)

Mixed-type AIHA:

• Idiopathic Idiopathic Dermatomyositis
• Secondary ( lymphoproliferative disorders Lymphoproliferative disorders Disorders characterized by proliferation of lymphoid tissue, general or unspecified. Lymphocytosis, autoimmune disorders)

Specific causes of AIHAs

Pathophysiology

Warm AIHA

• Warm autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques are responsible for the majority of AIHA cases.
• 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 (predominantly IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis) interact with Rhesus factor Rhesus factor Blood Group Systems (Rh) complex antigens or glycoprotein antigens.
• Warm autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques react more strongly at 37°C.
• Pathogenesis:
  • In most cases, hemolysis (facilitated by phagocytic cells) occurs extravascularly.
  • RBC destruction occurs where macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation are abundant, mostly 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 (also in liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy 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):
    • Fc Fc Crystallizable fragments composed of the carboxy-terminal halves of both immunoglobulin heavy chains linked to each other by disulfide bonds. Fc fragments contain the carboxy-terminal parts of the heavy chain constant regions that are responsible for the effector functions of an immunoglobulin (complement fixation, binding to the cell membrane via fc receptors, and placental transport). This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme papain. Immunoglobulins: Types and Functions portion (antibody) is recognized by Fc Fc Crystallizable fragments composed of the carboxy-terminal halves of both immunoglobulin heavy chains linked to each other by disulfide bonds. Fc fragments contain the carboxy-terminal parts of the heavy chain constant regions that are responsible for the effector functions of an immunoglobulin (complement fixation, binding to the cell membrane via fc receptors, and placental transport). This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme papain. Immunoglobulins: Types and Functions receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors of phagocytes → phagocytosis Phagocytosis The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (phagocytes). Innate Immunity: Phagocytes and Antigen Presentation of heavy chain of IgG IgG The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of igg, for example, igg1, igg2a, and igg2b. Hypersensitivity Pneumonitis and part of the 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 → spherocyte formed
    • Cytotoxic Cytotoxic Parvovirus B19 T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions 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 → cell-mediated cytotoxicity → RBC hemolysis
    • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation recognize complement C3 Complement C3 A glycoprotein that is central in both the classical and the alternative pathway of complement activation. C3 can be cleaved into complement C3a and complement C3b, spontaneously at low level or by C3 convertase at high level. The smaller fragment C3a is an anaphylatoxin and mediator of local inflammatory process. The larger fragment C3b binds with C3 convertase to form C5 convertase. Membranoproliferative Glomerulonephritis fragments → 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 with complements are phagocytosed.
• Over 95% of warm AIHA cases have a positive direct antiglobulin test (DAT) or Coombs test.

Cold AIHA

Cold-sensitive autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques react more strongly at 0–4℃.

• Cold agglutinins:
  • 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 (predominantly 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) interact with RBC I antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination or i antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination below normal core temperature:
    • I antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination: present in 99% of the population
    • i antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination: noted in < 1% 
  • After binding 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, 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 autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques activate the classic complement cascade Complement cascade 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. C3 Deficiency (C1 → C3b).
  • 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 coated with C3b undergo phagocytosis Phagocytosis The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (phagocytes). Innate Immunity: Phagocytes and Antigen Presentation extravascularly (in the reticuloendothelial system, mostly by Kupffer cells Kupffer cells Specialized phagocytic cells of the mononuclear phagocyte system found on the luminal surface of the hepatic sinusoids. They filter bacteria and small foreign proteins out of the blood, and dispose of worn out red blood cells. Benign Liver Tumors in the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy)
  • Results in extravascular hemolysis Extravascular hemolysis Hemolytic Anemia
  • Upon warming, 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 dissociates, but C3b remains and is, thus, detected on DAT.
• Donath-Landsteiner 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:
  • Recognize RBC antigens (often the P antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination) in cold temperature and fix complement, leading to hemolysis 
  • Intravascular hemolysis Intravascular hemolysis Hemolytic Anemia → 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 and 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
  • Found in PCH

Clinical Presentation

• 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:
  • Shortness of breath Shortness of breath 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
  • 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
  • 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
  • Pallor
  • Palpitations Palpitations Ebstein’s Anomaly
• Extravascular hemolysis Extravascular hemolysis Hemolytic Anemia:
  • 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 
  • Gallstones Gallstones Cholelithiasis (gallstones) is the presence of stones in the gallbladder. Most gallstones are cholesterol stones, while the rest are composed of bilirubin (pigment stones) and other mixed components. Patients are commonly asymptomatic but may present with biliary colic (intermittent pain in the right upper quadrant). Cholelithiasis
  • 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
  • Hepatomegaly
  • Lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy 
• Intravascular hemolysis Intravascular hemolysis Hemolytic Anemia:
  • Dark urine ( 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)
  • Transient 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

Cold AIHA:

• Acrocyanosis Acrocyanosis Physical Examination of the Newborn:
  • Dark gray or purple discoloration of toes, fingers, ears, or nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal) on exposure to cold 
  • Can result in gangrene Gangrene Death and putrefaction of tissue usually due to a loss of blood supply. Small Bowel Obstruction in severe cases
• Raynaud phenomenon
• Livedo reticularis Livedo reticularis A condition characterized by a reticular or fishnet pattern on the skin of lower extremities and other parts of the body. This red and blue pattern is due to deoxygenated blood in unstable dermal blood vessels. The condition is intensified by cold exposure and relieved by rewarming. Chronic Kidney Disease: skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions with bluish or violaceous reticulated pattern that blanches

Diagnosis

Initial laboratory evaluation

Diagnosis is with evidence of hemolysis and positive DAT.

• 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
  • MCV varies with 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
  • Usually normal leukocyte and platelet counts Platelet counts The number of platelets per unit volume in a sample of venous blood. Coagulation Studies
• 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: usually increased
• Peripheral blood smear Peripheral Blood Smear Anemia: Overview and Types:
  • Polychromasia (due to high 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 counts)
  • Spherocytes
  • Schistocytes Schistocytes Hemolytic Uremic Syndrome
  • Nucleated 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
  • RBC clumps
• DAT:
  • Establishes the diagnosis
  • Identifies 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 and/or complement bound on 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
  • Strength of positive test correlates with severity of hemolysis.
  • Warm AIHA:
    • Positive at  37°C for anti-IgG 
    • Anti-C3 may or may not be positive. 
  • Cold AIHA: positive for anti-C3 and negative for anti-IgG
• Serum markers of hemolysis:
  • ↑ Indirect bilirubin Indirect Bilirubin Liver Function Tests
  • ↑ LDH LDH Osteosarcoma 
  • ↑ 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 and ALT ALT An enzyme that catalyzes the conversion of l-alanine and 2-oxoglutarate to pyruvate and l-glutamate. Liver Function Tests  
  • Low serum haptoglobin 
• C3 and C4 levels reduced in cold AIHA 
• Cold agglutinin titer: high titer in cold AIHA

Additional evaluation

• 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, both dipstick and microscopic:
  • 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 → dipstick positive for blood but absence 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
  • 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 normal in extravascular hemolysis Extravascular hemolysis Hemolytic Anemia
• BUN/creatinine: renal impairment in intravascular hemolysis Intravascular hemolysis Hemolytic Anemia
• Review possible secondary causes:
  • Underlying conditions 
  • Recent 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 (i.e., serologic testing positive for Mycoplasma pneumoniae Mycoplasma pneumoniae Short filamentous organism of the genus mycoplasma, which binds firmly to the cells of the respiratory epithelium. It is one of the etiologic agents of non-viral primary atypical pneumonia in man. Mycoplasma)
  • Medications
  • Transfusion 
• Bone marrow aspiration Bone marrow aspiration Removal of bone marrow and evaluation of its histologic picture. Severe Congenital Neutropenia on relevant indications (i.e., to exclude CLL CLL Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia)

Management

Principles of management

• Stabilization of the patient:
  • Assess severity of 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 and associated symptoms (i.e., 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 or those associated with cardiac ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage).
  • Hemodynamic and ventilatory support as needed
  • Determine need for transfusion (transfuse when necessary).
  • Discontinue suspected offending drug.
• Treatment of underlying condition, if present, is recommended.
• Hemolysis will continue for up to 3 weeks (equivalent to the half-life Half-Life The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity. Pharmacokinetics and Pharmacodynamics of autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques).

Warm AIHA

• Folic acid supplementation: Folate deficiency Folate deficiency A nutritional condition produced by a deficiency of folic acid in the diet. Many plant and animal tissues contain folic acid, abundant in green leafy vegetables, yeast, liver, and mushrooms but destroyed by long-term cooking. Alcohol interferes with its intermediate metabolism and absorption. Folic acid deficiency may develop in long-term anticonvulsant therapy or with use of oral contraceptives. This deficiency causes anemia, macrocytic anemia, and megaloblastic anemia. It is indistinguishable from vitamin B12 deficiency in peripheral blood and bone marrow findings, but the neurologic lesions seen in B12 deficiency do not occur. Megaloblastic Anemia can develop with chronic hemolysis.
• Glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids +/– rituximab Rituximab A murine-derived monoclonal antibody and antineoplastic agent that binds specifically to the cd20 antigen and is used in the treatment of leukemia; lymphoma and rheumatoid arthritis. Immunosuppressants:
  • May start with both as initial treatment, OR
  • Initiate rituximab Rituximab A murine-derived monoclonal antibody and antineoplastic agent that binds specifically to the cd20 antigen and is used in the treatment of leukemia; lymphoma and rheumatoid arthritis. Immunosuppressants if no response with glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids after 2–3 weeks
• Intravenous immunoglobulin ( IVIG IVIG Dermatomyositis)
• Refractory disease:
  • Immunosuppressants Immunosuppressants Immunosuppressants are a class of drugs widely used in the management of autoimmune conditions and organ transplant rejection. The general effect is dampening of the immune response. Immunosuppressants: mycophenolate Mycophenolate Immunosuppressants, cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants, or azathioprine Azathioprine An immunosuppressive agent used in combination with cyclophosphamide and hydroxychloroquine in the treatment of rheumatoid arthritis. According to the fourth annual report on carcinogens, this substance has been listed as a known carcinogen. Immunosuppressants
  • Splenectomy Splenectomy Surgical procedure involving either partial or entire removal of the spleen. Rupture of the Spleen

Cold AIHA

• Avoid cold.
• Folic acid supplementation
• Immunosuppressants Immunosuppressants Immunosuppressants are a class of drugs widely used in the management of autoimmune conditions and organ transplant rejection. The general effect is dampening of the immune response. Immunosuppressants: rituximab-containing regimens (i.e., rituximab Rituximab A murine-derived monoclonal antibody and antineoplastic agent that binds specifically to the cd20 antigen and is used in the treatment of leukemia; lymphoma and rheumatoid arthritis. Immunosuppressants with bendamustine Bendamustine A nitrogen mustard compound that functions as an alkylating antineoplastic agent and is used in the treatment of chronic lymphocytic leukemia and non-Hodgkin’s lymphoma. Alkylating Agents and Platinum)
• Plasmapheresis Plasmapheresis Procedure whereby plasma is separated and extracted from anticoagulated whole blood and the red cells retransfused to the donor. Plasmapheresis is also employed for therapeutic use. Stevens-Johnson Syndrome in cases of severe hemolysis

Complications and prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

Warm AIHA:

• ↑ Risk of venous thromboembolism Thromboembolism Obstruction of a blood vessel (embolism) by a blood clot (thrombus) in the blood stream. Systemic Lupus Erythematosus:
  • Rule out deep vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus if D-dimer D-dimer Deep Vein Thrombosis positive.
  • Rule out 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 if 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 is disproportionate 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.
• Evans syndrome:
  • 2 or more immune cytopenias Cytopenias IPEX Syndrome occur concurrently.
  • AIHA can present with immune-mediated thrombocytopenic purpura ( ITP ITP Immune thrombocytopenic purpura (ITP), formerly known as idiopathic thrombocytopenic purpura, is a condition that develops secondary to immune-mediated destruction of platelets, resulting in thrombocytopenia (platelet count < 100,000/mm³). Immune thrombocytopenic purpura can be either primary or secondary due to drugs or underlying disease. Immune Thrombocytopenic Purpura).
  • Associated with higher mortality Mortality All deaths reported in a given population. Measures of Health Status rate
• Majority of cases respond to therapy in 2–3 weeks.
• Relapse Relapse Relapsing Fever is possible, and patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship should be educated to seek medical care Medical care Conflict of Interest if symptoms recur.

Cold AIHA:

• Survival similar to that of age-matched populations
• In viral-associated PCH affecting children, recovery is seen within 2 weeks.
• Recurrent episodes are more often seen in adults.

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: group of anemias that are due to destruction or premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis clearance 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. Hemolysis can be either intravascular or extravascular (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). The etiology of premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis erythrocyte destruction is diverse and can be due to conditions such as RBC membrane defects, erythrocyte enzymatic defects, immune destruction of 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, mechanical injury, and hypersplenism Hypersplenism Condition characterized by splenomegaly, some reduction in the number of circulating blood cells in the presence of a normal or hyperactive bone marrow, and the potential for reversal by splenectomy. Splenomegaly. In non-autoimmune causes of 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, the DAT is characteristically negative.
• System lupus erythematosus ( SLE SLE Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus): chronic, autoimmune, inflammatory condition that causes immune complex deposition in organs, resulting in systemic manifestations. This disease overwhelmingly affects women, particularly those of African American descent. Notable clinical features include a malar rash Malar Rash Systemic Lupus Erythematosus, nondestructive arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis, lupus nephritis Lupus nephritis Glomerulonephritis associated with autoimmune disease systemic lupus erythematosus. Lupus nephritis is histologically classified into 6 classes: class I – normal glomeruli, class II – pure mesangial alterations, class III – focal segmental glomerulonephritis, class IV – diffuse glomerulonephritis, class V – diffuse membranous glomerulonephritis, and class VI – advanced sclerosing glomerulonephritis (the world health organization classification 1982). Diffuse Proliferative Glomerulonephritis, serositis Serositis Inflammation of a serous membrane. Systemic Lupus Erythematosus, cytopenias Cytopenias IPEX Syndrome, thromboembolic disease, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, and/or psychosis. The diagnosis is made by meeting clinical criteria, which includes antinuclear 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, SLE-specific antibodies SLE-specific antibodies Systemic Lupus Erythematosus, and specific clinical findings.
• Chronic lymphocytic leukemia Chronic Lymphocytic Leukemia Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia: most common leukemia in adults. Chronic lymphocytic leukemia Chronic Lymphocytic Leukemia Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia is a monoclonal B-cell proliferation that infiltrates the 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 or lymph nodes Lymph Nodes They are oval or bean shaped bodies (1 – 30 mm in diameter) located along the lymphatic system. Lymphatic Drainage System: Anatomy. The B cells B cells Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation. B cells: Types and Functions arrest before maturation, and thus these patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship have agammaglobulinemia, resulting in recurrent infections Recurrent infections Common Variable Immunodeficiency (CVID). Chronic lymphocytic leukemia Chronic Lymphocytic Leukemia Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia is mainly found incidentally on blood work showing lymphocytosis Lymphocytosis WBCs develop from stem cells in the bone marrow and are called leukocytes when circulating in the bloodstream. Lymphocytes are 1 of the 5 subclasses of WBCs. Lymphocytosis is an increase in the number or proportion of the lymphocyte subclass of WBCs, often as a result of an immune response to infection (known as reactive lymphocytosis). Lymphocytosis. Peripheral smears show smudge cells Smudge Cells Chronic Lymphocytic Leukemia. Chronic lymphocytic leukemia Chronic Lymphocytic Leukemia Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia is a leading secondary cause of both warm and cold AIHA and should be considered in cases of AIHA associated with massive splenomegaly Massive Splenomegaly Splenomegaly or lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy.
• Cryoglobulinemia Cryoglobulinemia A condition characterized by the presence of abnormal quantities of cryoglobulins in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas. Rapidly Progressive Glomerulonephritis: disorder due to immunoglobulins Immunoglobulins 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 (cryoglobulins) that precipitate in cold temperatures (below 37℃).  Cryoglobulinemia Cryoglobulinemia A condition characterized by the presence of abnormal quantities of cryoglobulins in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas. Rapidly Progressive Glomerulonephritis is associated with arthralgias, glomerulonephritis, purpura, or peripheral neuropathy Neuropathy Leprosy. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship can also exhibit cold-induced Raynaud phenomenon. History of infection (usually hepatitis C Hepatitis C Hepatitis C is an infection of the liver caused by the hepatitis C virus (HCV). The infection can be transmitted through infectious blood or body fluids and may be transmitted during childbirth or through IV drug use or sexual intercourse. Hepatitis C virus can cause both acute and chronic hepatitis, ranging from a mild to a serious, lifelong illness including liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis C Virus virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology) is associated with cryoglobulinemia Cryoglobulinemia A condition characterized by the presence of abnormal quantities of cryoglobulins in the blood. Upon cold exposure, these abnormal proteins precipitate into the microvasculature leading to restricted blood flow in the exposed areas. Rapidly Progressive Glomerulonephritis. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship will not have cold agglutinin on laboratory testing, and most do not have AIHA.