Question

A patient who was given primaquine develops hemolysis. The probable cause may be:

• A. Glucose-6-phosphate dehydrogenase deficiency
• B. Glucose-6-phosphatase deficiency
• C. Alpha-ketoglutarate dehydrogenase deficiency
• D. Pyruvate kinase deficiency

Hint:

Oxidant drug plus red-cell hemolysis points to the enzyme that supplies NADPH.

Answer 1

The Correct Option is A

Step 1: Link the drug to oxidative stress. Primaquine is a classic oxidant drug that generates reactive oxygen species inside red blood cells.
Step 2: Recall how RBCs defend against oxidants. Red cells rely on reduced glutathione (GSH) to neutralize oxidants, and regenerating GSH requires NADPH.
Step 3: Identify the source of NADPH. In the erythrocyte, NADPH is produced almost entirely by the hexose monophosphate (pentose phosphate) pathway, whose rate-limiting enzyme is glucose-6-phosphate dehydrogenase (G6PD).
Step 4: Connect deficiency to hemolysis. In G6PD deficiency, NADPH and therefore GSH cannot be maintained, so an oxidant like primaquine overwhelms the cell, causing hemoglobin denaturation (Heinz bodies) and acute hemolysis.
Step 5: Exclude the others. Glucose-6-phosphatase deficiency causes von Gierke disease, alpha-ketoglutarate dehydrogenase is a TCA enzyme, and pyruvate kinase deficiency causes chronic non-oxidant hemolysis, not the primaquine-triggered pattern.
Conclusion: The cause is G6PD deficiency, so the correct answer is option 1.