A 48-year-old man with chronic alcoholism has MCV 104 fL, round macrocytes on smear, no hypersegmented neutrophils, and mild thrombocytopenia. Vitamin B12 and folate levels are normal. What is the most likely basis of his macrocytosis?
- A Early myelodysplastic syndrome
- B Occult gastrointestinal blood loss with regenerative reticulocytosis
- C Direct toxic effect of alcohol on marrow causing membrane lipid abnormality in red cells ✓
- D Hypothyroidism-induced macrocytosis
Correct answer: C. Direct toxic effect of alcohol on marrow causing membrane lipid abnormality in red cells
Explanation
Non-megaloblastic macrocytosis of chronic alcoholism and liver disease arises from excess membrane lipid deposition in circulating red cells, producing round macrocytes without megaloblastic changes or hypersegmented neutrophils. Reticulocytosis also enlarges MCV, but chronic alcoholic marrow suppression makes a regenerative response unlikely, killing option B. Hypothyroidism and myelodysplasia are genuine causes of non-megaloblastic macrocytosis but are not supported by the history given.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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