Pyruvate kinase (PK) deficiency is the most common red cell glycolytic enzyme deficiency causing hereditary non-spherocytic hemolytic anemia. The mechanism of hemolysis is best explained by:

• A Failure of HMP shunt to regenerate NADPH leads to glutathione oxidation
• B Decreased ATP production from glycolysis impairs Na+/K+-ATPase pump, causing RBC swelling and lysis ✓
• C Accumulation of 2,3-BPG destabilizes hemoglobin tetramers
• D Pyruvate accumulation in RBCs inhibits glutathione peroxidase

Explanation

RBCs rely exclusively on glycolysis (Embden-Meyerhof pathway) for ATP generation. PK deficiency reduces pyruvate kinase activity, diminishing ATP production. Without ATP, the Na+/K+-ATPase cannot maintain ionic gradients; sodium and water influx causes osmotic swelling and hemolysis. Additionally, 2,3-BPG (2,3-bisphosphoglycerate) accumulates upstream of the PK block — a compensatory benefit (right-shifts oxyhemoglobin curve) but does not directly cause hemolysis. G6PD deficiency (not PK) impairs the HMP shunt.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

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