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Haemolytic Transfusion Reaction AKI — ESENeph MCQ

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ModerateAcute Kidney InjuryHaemolytic Transfusion Reaction AKIESENeph

A 40-year-old man develops AKI with haemoglobinuria after a blood transfusion. He has sickle cell trait. His urine is dark brown and dipstick-positive for blood but microscopy shows no red cells. Direct Coombs test is positive. Creatinine rises from 75 to 280 umol/L. What is the mechanism of AKI?

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Correct answer: E — Acute haemolytic transfusion reaction causing haemoglobinuria with direct tubular toxicity and tubular obstruction from haemoglobin casts

Acute haemolytic transfusion reaction (ABO incompatibility or other antibody-mediated) causes intravascular haemolysis, releasing free haemoglobin. Like myoglobin, free haemoglobin is directly nephrotoxic through: (1) tubular obstruction from haemoglobin casts; (2) oxidative injury to tubular cells; (3) renal vasoconstriction from nitric oxide scavenging. The positive direct Coombs test confirms immune-mediated haemolysis. Management includes stopping the transfusion, aggressive IV hydration, and potentially urinary alkalinisation. In dialysis-eligible patients (e.g. transplant candidates), this underscores the importance of avoiding unnecessary transfusions.

Reference: KDIGO 2012 – AKI; SHOT Annual Report – Transfusion Reactions