MCQ – 4625

About HUS all are true except :

A.	Not commonly caused by verocytogenic E coli
B.	Causes mild to severe Coombs positive hemolytic anemia
C.	Recurrences rare
D.	Transient thrombocytopenia

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Correct Answer » B Explanation

Hemolytic Uremic Syndrome (HUS) is a form of thrombotic microangiopathy characterized by the classical triad:

• Microangiopathic hemolytic anemia

• Thrombocytopenia

• Acute kidney injury

It is most commonly seen in children following diarrheal illness.

Etiopathogenesis

• Most common cause: Verotoxin (Shiga-like toxin) producing Escherichia coli (E. coli O157:H7)

• The toxin causes:

  • Endothelial injury (especially in renal vasculature)

  • Platelet activation and aggregation

  • Formation of microthrombi

• RBCs passing through these damaged vessels undergo mechanical fragmentation, leading to hemolysis.

Nature of Hemolysis

• Hemolysis in HUS is:

  • Microangiopathic

  • Coombs negative

• Peripheral smear shows:

  • Schistocytes (helmet cells)