A 40-year-old woman started on zidovudine-based antiretroviral therapy returns after 8 weeks with fatigue and pallor. Hemoglobin is 7.8 g/dL and MCV is 112 fL. The most likely explanation for this presentation is:

• A Mitochondrial DNA polymerase gamma inhibition causing lactic acidosis
• B Parvovirus B19 induced pure red cell aplasia
• C Immune reconstitution inflammatory syndrome
• D Inhibition of host bone marrow DNA synthesis by the drug ✓

Explanation

Zidovudine is the NRTI most associated with bone marrow suppression, producing macrocytic anemia and neutropenia, typically within the first few months of therapy. The macrocytosis reflects impaired DNA synthesis in erythroid precursors. Option A describes the separate mitochondrial toxicity syndrome of lactic acidosis with hepatic steatosis, not anemia.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.