Self-limited intravascular hemolysis after eating fava beans suggests which deficiency?

Self-limited intravascular hemolysis after eating fava beans suggests which deficiency?

• A. Sickle cell disease
• B. Glucose-6-phosphate deficiency
• C. Pyruvate kinase deficiency
• D. Gaucher disease

Answer: (B)

The key idea is that oxidative stress can trigger red cell destruction when the defense against oxidation is impaired. Glucose-6-phosphate dehydrogenase deficiency impairs the pentose phosphate pathway, which normally makes NADPH. NADPH keeps glutathione in the reduced form to detoxify reactive oxygen species. Fava beans contain oxidative compounds that overwhelm red cells; in someone with G6PD deficiency, the lack of NADPH means red cells can’t neutralize these oxidants, leading to intravascular hemolysis. This hemolysis is often self-limited because it occurs only during exposure to the oxidative stress and the body compensates with increased reticulocytes as the crisis resolves. The pattern fits favism and is characteristic of G6PD deficiency, a condition that also explains why other red cell disorders like sickle cell disease, pyruvate kinase deficiency, or Gaucher disease don’t produce this specific trigger-response pattern.

The key idea is that oxidative stress can trigger red cell destruction when the defense against oxidation is impaired. Glucose-6-phosphate dehydrogenase deficiency impairs the pentose phosphate pathway, which normally makes NADPH. NADPH keeps glutathione in the reduced form to detoxify reactive oxygen species. Fava beans contain oxidative compounds that overwhelm red cells; in someone with G6PD deficiency, the lack of NADPH means red cells can’t neutralize these oxidants, leading to intravascular hemolysis. This hemolysis is often self-limited because it occurs only during exposure to the oxidative stress and the body compensates with increased reticulocytes as the crisis resolves. The pattern fits favism and is characteristic of G6PD deficiency, a condition that also explains why other red cell disorders like sickle cell disease, pyruvate kinase deficiency, or Gaucher disease don’t produce this specific trigger-response pattern.