Myasthenia Gravis
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Overview Definition Myasthenia gravis (MG) is a chronic autoimmune disorder in which antibodies attack the acetylcholine receptor (AChR) complex at the neuromuscular junction. Epidemiology Etiology Classification and Pathophysiology Classification There are 2 main clinical forms of MG: In addition, rarer forms of MG exist that primarily affect the pediatric population: Myasthenia gravis may also be […]
Lambert-Eaton Myasthenic Syndrome
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Overview Definition Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder affecting the neuromuscular junction and has a strong association with small cell lung carcinoma. Epidemiology Etiology Pathophysiology and Clinical Presentation Pathophysiology Clinical presentation Muscle weakness: Bulbar involvement: Autonomic dysfunction: Respiratory failure: Diagnosis History and physical exam Electrodiagnostic studies Antibody tests Cancer screening Management Management General: […]
Disseminated Intravascular Coagulation
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Overview Definition Disseminated intravascular coagulation (DIC) is a condition characterized by systemic bodywide activation of the coagulation cascade that results in both: Epidemiology Classification Acute DIC: Chronic DIC: Etiology Disseminated intravascular coagulation is always a complication of other conditions: Table: Etiologies of disseminated intravascular coagulation Infection Bacterial: Sepsis (both gram-positive and gram-negative species) Escherichia coli […]
Short Bowel Syndrome
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Overview Definition Epidemiology Etiology Pathophysiology Physiology Consequences of bowel resection Several factors determine the degree of intestinal function loss after bowel resection: Phases of SBS Acute phase: Adaptation phase: Maintenance phase: Clinical Presentation and Diagnosis General clinical presentation Nutritional deficiencies Laboratory findings The following table summarizes possible laboratory findings in SBS that correlate with signs […]
Renal Sodium and Water Regulation
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Background Concepts Fluid compartments To understand renal sodium and water regulation, it is important to understand how water is normally distributed in the body. Total body water (TBW): Intracellular fluid (ICF): Extracellular fluid (ECF): Osmolality Plasma osmolality refers to the combined concentration of all solutes in the blood. Tonicity Plasma tonicity refers to the concentration […]
Wilms Tumor
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Overview Epidemiology Etiology Pathophysiology Clinical Presentation Manifestations Physical examination Diagnosis Screening Serial abdominal ultrasonography for those at risk for Wilms tumor: Diagnostic imaging and laboratory studies Staging From National Wilms Tumor Study (NWTS)/Children’s Oncology Group (COG): Management Treatment Recommendations based on the NWTS/COG trials: Prognosis Differential Diagnosis References
Osteochondritis Dissecans
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Overview Definition Osteochondritis dissecans (OCD) is a disorder characterized by aseptic necrosis of subchondral bone that results in focal detachment and displacement of bone and cartilage into the joint space. The term osteochondritis is a misnomer, as histologic analysis reveals a lack of inflammatory cells. Epidemiology Etiology and Pathophysiology Etiology The exact etiology is unknown. […]
Respiratory Failure
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Definition and Classification Definition Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Classification Respiratory failure may be classified based on: The time course: The underlying issue: Etiology Etiology of hypoxemic respiratory failure Etiology of hypercapnic respiratory failure Pathophysiology Right-to-left shunt Ventilation-to-perfusion inequality A mismatch between […]
Hyperkalemia
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Overview General considerations K+ is the main intracellular cation in all cells and is distributed unevenly between the intracellular fluid (98%) and extracellular fluid (2%). Sites of action in the kidney Normal response to ingested K+ A normal Western diet contains approximately 70–150 mmol of K+ per day. This diet is unlikely to lead to […]
Coagulation Studies
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Overview Definition Coagulation studies are a group of hematologic studies that reflect the function of blood vessels, platelets, and coagulation factors, which all work in harmony to achieve hemostasis. Uses of coagulation studies Review: phases of the hemostatic process The following is a summary of the hemostatic process: Coagulation Studies The following studies can assist […]