A 48-year-old man with chronic alcoholism has MCV 106 fL and hemoglobin 11.2 g/dL. The smear shows round macrocytes and target cells but no hypersegmented neutrophils. Serum methylmalonic acid and homocysteine are normal, and bone marrow shows no megaloblastic changes. The macrocytosis is best explained by:
- A Impaired DNA synthesis from folate trap phenomenon
- B Altered red cell membrane lipid composition due to liver disease ✓
- C Autoantibody mediated parietal cell destruction
- D Excess erythropoietin driven reticulocyte release
Explanation
Non-megaloblastic macrocytosis occurs in alcoholism and chronic liver disease because disordered cholesterol and phospholipid metabolism expands the red cell membrane without impairing DNA synthesis. Hence round macrocytes, target cells, normal methylmalonic acid and homocysteine, and absence of hypersegmented neutrophils or megaloblastic marrow. The folate trap and parietal cell destruction produce megaloblastic anemia with hypersegmented neutrophils, while reticulocytosis causes polychromasia and would be accompanied by a high reticulocyte count, none of which are described here.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.