Demystifying the Mystery of Vitamin B12 Deficiency in an Infant with Developmental Delay

A 7-month-old boy presented to our hospital with complaints of epistaxis. Pancytopenia was found on a blood test, and physical examination significant for hepatosplenomegaly, acral hyperpigmentation hands feet, hypotonia, along mild delayed milestones. The infant underwent extensive investigations including metabolic workup bone marrow aspiration, which revealed abundant megalocytes. Vitamin B12 deficient (result 82 pg/mL, reference range 187–883 pg/mL); therefore, vitamin therapy commenced. Following the initiation therapy, cell lines normalized, neurological symptoms improved, hepatosplenomegaly regressed, milestones were achieved.