Erythropoietin-stimulating agent-resistant vitamin B₆ deficiency anemia in a pediatric patient on hemodialysis

Vitamin B₆ is a rate-limiting coenzyme that plays an important role in the biosynthesis of heme and the incorporation of iron into protoporphyrin. Its deficiency is often seen in chronic kidney disease (CKD), particularly those requiring dialysis and following administration of erythropoietin-stimulating agent (ESA).

A 16-year-old African-American male with stage 5 CKD on chronic hemodialysis experienced a decrease in hemoglobin over a 3-month period from 11 to 6.5 g/dl while receiving ESA, resulting in multiple blood transfusions. His transferrin saturation was 41%, ferritin level 706 [80–388] ng/mL, mean corpuscular volume (MCV) 87 [78–98] μm³, corrected reticulocytes count 2.3% [0.2–1.8%], and vitamin B₆ 1.2 [5.3–46.7] μg/L. Bone marrow biopsy was normocellular (65%) with erythroid hyperplasia and rare dyserythropoiesis. Prussian blue staining showed increased iron storage. Supplemental vitamin B₆ (100 mg daily) was initiated at hemoglobin 7.3 g/dL with correction of anemia. Eighteen months later, his hemoglobin is 11.7 g/dL, transferrin saturation 45%, with no additional blood transfusions.

Vitamin B₆ deficiency anemia should be considered in any pediatric patient on hemodialysis who does not respond to standard ESA and iron therapy.