Review Question - QID 109545

This patient is presenting with a megaloblastic anemia and hypersegmented neutrophils suggesting vitamin B12 and folate deficiency. Folate is more likely to be depleted in alcoholic patients and is required for the proper functioning of methionine synthase.

Alcoholism predisposes patients to various deficiencies including glucose, vitamin B12, folic acid, magnesium, and thiamine. A deficiency of vitamin B12 and folate can lead to a megaloblastic anemia as well as hypersegmented neutrophils on peripheral smear. Folic acid reserves are typically depleted first in alcoholic patients. Both folic acid and vitamin B12 are required for methionine synthase to function properly.

Figure A is a peripheral smear that demonstrates macrocytosis and hypersegmented neutrophils, which are commonly seen in folate and B12 deficiency.

Incorrect Answers:
Answer 2: Methylmalonyl CoA mutase requires vitamin B12 as a cofactor. Vitamin B12 deficiency can present with megaloblastic anemia and hypersegmented neutrophils; however, folate reserves are depleted more quickly than are B12 reserves. For this reason, folate is more likely to be deficient in an alcoholic.

Answer 3: Transketolase utilizes thiamine as a cofactor. Thiamine is classically deficient in alcoholics who present with Wernicke-Korsakoff psychosis. In the setting of this patient's megaloblastic anemia and hypersegmented neutrophils, folate is more likely deficient.

Answer 4: Pyruvate dehydrogenase requires cofactors of magnesium and thiamine. This patient is more likely to be deficient in folate given his hematologic findings.

Answer 5: Cystathionine synthase utilizes pyridoxine (vitamin B6) as a cofactor, which is less likely to be depleted in this anemic and alcoholic patient.

Bullet Summary:
Folic acid is frequently depleted in alcoholic patients and is a cofactor for the enzyme methionine synthase.