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Pathology · Haematology: G6PD deficiency
Sample itemAn 8-year-old boy develops dark urine, jaundice and a fall in haemoglobin 2 days after eating fava beans. Supravital staining of his blood shows inclusions attached to the red cell membrane, and the smear shows cells with a bitten-out edge. What do these inclusions represent?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
A. Precipitates of denatured haemoglobin (Heinz bodies)
In G6PD deficiency red cells cannot regenerate NADPH, so glutathione cannot neutralise oxidants from fava beans, infections or drugs such as primaquine. Haemoglobin is oxidised and precipitates as Heinz bodies, which splenic macrophages pit out, leaving bite cells. The condition is X-linked recessive, so affected patients are mostly male.
Option by option
A. Precipitates of denatured haemoglobin (Heinz bodies) (correct)
Correct. Oxidant stress denatures haemoglobin into Heinz bodies, seen on supravital stains.
B. Nuclear remnants within red cells (Howell-Jolly bodies)
Howell-Jolly bodies are DNA remnants seen after splenectomy or in hyposplenism.
C. Aggregates of ribosomal RNA (basophilic stippling)
Basophilic stippling represents ribosomal RNA aggregates, as in lead poisoning.
D. Iron-laden granules (Pappenheimer bodies)
Pappenheimer bodies are iron granules seen in sideroblastic anaemia and after splenectomy.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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