Hemolytic Uremic Syndrome Pathophysiology: HUS is characterized by the triad of symptoms: hemolytic anemia, thrombocytopenia, and acute renal failure. It is often associated with infections, particularly those caused by enterohemorrhagic Escherichia coli (EHEC), also known as Shiga toxin-producing E. coli. The toxin produced by these bacteria damages endothelial cells in the kidneys, leading to platelet aggregation and formation of microthrombi, which results in acute renal injury. Clinical Presentation:  Hemolytic Anemia: Similar to TTP, with elevated LDH, low haptoglobin, and elevated indirect bilirubin.  Thrombocytopenia: Resulting in bleeding symptoms and purpura.  Acute Renal Failure: Ranges from elevated serum creatinine to oliguria or anuria.  Gastrointestinal Symptoms: Often precedes HUS, including diarrhea (often bloody). Diagnosis:  Clinical Criteria: Diagnosis is based on the triad of hemolytic anemia, thrombocytopenia, and renal failure.  Stool Culture: To identify E. coli O157 or other pathogens.  Blood Tests: To assess anemia and renal function. Management:  Supportive Care: Includes hydration and management of renal failure.  Antibiotics: Generally avoided in HUS as they may worsen the condition; supportive care is preferred.  Plasma Exchange: Not typically used for HUS, unlike TTP. Prognosis: The prognosis for TTP and HUS varies. TTP can be life-threatening but often has a good prognosis with prompt treatment. HUS has a variable prognosis depending on the severity of renal involvement and the presence of underlying infections. Both conditions require early recognition and appropriate management to reduce complications and improve outcomes. Regular monitoring and supportive care are essential for both disorders.