This patient most likedly has a diagnosis of macrocytic anemia. The most likely causes of the findings seen on the peripheral smear are due to a folate deficiency.
This patient’s peripheral smear demonstrates a macrocytic anemia with hypersegmented neutrophils. The most common causes of folate deficiency are poor nutrition, alcohol abuse, and certain medications, such as trimethoprim, pyrimethamine, methotrexate, and phenytoin. In light of the history that this patient’s drinking increased as recently as several months ago, it is most likely that his anemia is caused by a folate deficiency. Folate deficiency can develop within 4-5 months, whereas vitamin B12 stores take years to deplete. In addition, while serum homocysteine levels are elevated in both folate and vitamin B12 deficiencies, serum methylmalonic acid levels are normal in folate deficiency and elevated in vitamin B12 deficiency.
Figure A demonstrates the macrocytic, megaloblastic anemia with hypersegmented neutrophils seen in both folate and vitamin B12 deficiency. Illustration A demonstrates the microcytic, hypochromic anemia seen in iron deficiency anemia.
Answer 1: Alcohol withdrawal would not cause hematologic changes seen on peripheral smear. In terms of the patient’s clinical picture, his presentation suggests a diagnosis of Wernicke encephalopathy rather than alcohol withdrawal.
Answer 2: This patient’s clinical presentation of Wernicke encephalopathy is caused by thiamine deficiency, but the thiamine deficiency does not cause the findings seen on peripheral smear. Wernicke encephalopathy is characterized by the classic triad of encephalopathy, oculomotor dysfunction (nystagmus being the most common), and gait ataxia.
Answer 3: Iron deficiency causes the microcytic, hypochromic anemia seen in Illustration A rather than a macrocytic, megaloblastic anemia.
Answer 5: Although vitamin B12 deficiency causes the same macrocytic, megaloblastic anemia, vitamin B12 deficiency takes years to develop, whereas folate deficiency usually takes 4-5 months. Because this patient only started drinking heavily a few months ago, folate deficiency is more likely.
Folate deficiency may develop within 4-5 months and is characterized by a macrocytic, megaloblastic anemia with hypersegmented neutrophils on peripheral smear. It can be differentiated from vitamin B12 deficiency by the absence of neurological symptoms and normal serum methylmalonic acid levels (which are elevated in vitamin B12 deficiency).