What is the most common enzymatic cause of hemolytic anemia?

• A. Pyruvate kinase deficiency
• B. G6PD deficiency
• C. Hereditary spherocytosis
• D. Sickle cell disease

Answer: (B)

G6PD deficiency is the most common enzymatic cause of hemolytic anemia. The enzyme in the pentose phosphate pathway generates NADPH, which keeps glutathione in its reduced form to protect red blood cells from oxidative damage. When G6PD is deficient, NADPH production drops, glutathione can’t neutralize oxidative stress effectively, and red cells become vulnerable to hemolysis. Triggers like infections, and drugs such as sulfonamides, dapsone, nitrofurantoin, and certain antimalarials, or even fava beans, provoke episodic intravascular and extravascular hemolysis. Other enzymatic defects, like pyruvate kinase deficiency, exist but are much less common. In contrast, hereditary spherocytosis and sickle cell disease stem from membrane and hemoglobin abnormalities, not enzyme defects, and cause hemolysis through different mechanisms.