Review Question - QID 104737

The patient in this vignette most likely has glucose-6-phosphate dehydrogenase (G6PD) deficiency as evidenced by hemolytic anemia induced by fava beans. The finding on peripheral smear is most consistent with bite cells.

G6PD deficiency is an X-linked recessive disease found most commonly in Greeks, Italians, and African Americans. Anemia is often precipitated by oxidant stresses that induce hemolysis. Infections are the most common cause, followed by drugs including dapsone, antimalarials, and sulfonamide antibiotics as well as food, including fava beans. The deficiency of G6PD reduces the synthesis of the reduced form of NADPH, which subsequently decreases glutathione (GSH) levels. Since GSH neutralizes hydrogen peroxide, the absence of GSH in G6PD deficiency allows peroxidase to oxidize hemoglobin.

Frank discusses the diagnosis and management of G6PD deficiency, concluding that diagnosis is best made by using a fluorescent spot test that assesses how readily NADPH is converted to its reduced form. Hemolysis is often self-limited and therapy should center around primary prevention via avoidance of oxidative stressors that precipitate hemolysis.

Mason et al. review clinical findings in G6PD deficiency anemia. Early findings include jaundice and elevated LDH levels. Blood smears often show anisocytosis, polychromasia, and poikilocytes with abnormal forms in the early stages of acute episodes.

Illustration A displays a image of a bite cell. Illustration B displays an image of Heinz body. Illustration C displays the enzymatic pathway involving G6PD.

Incorrect Answers:
Answer 2: Ringed sideroblasts are seen with lead poisoning.
Answer 3: Schistocytes are seen with disseminated intravascular coagulation.
Answer 4: Sphereocytes are seen with hereditary spherocytosis.
Answer 5: Target cells are seen with thalassemia.