Vitamin B6, Biotin, Folate & B12 | USMLE Step 1 Biochemistry
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A 42-year-old woman receiving isoniazid for latent tuberculosis develops fatigue and exertional dyspnea after four months of treatment. Hemoglobin has fallen from 12.8 to 8.9 g/dL (reference 12.0–16.0), and mean corpuscular volume is 73 fL (80–100). Ferritin is 310 ng/mL (15–150). A marrow iron stain shows iron-laden mitochondria surrounding erythroblast nuclei.
Pyridoxine is added to her regimen; the reticulocyte count rises over the following week.