Vitamin B12 deficiency with intrinsic factor antibodies in an infant with poor growth and developmental delay

Vitamin B₁₂ deficiency is very rare in infants and may lead to serious hematological and neurodevelopmental abnormalities. The present article describes a case involving a seven-month-old boy with severe vitamin B₁₂ deficiency, likely caused by juvenile pernicious anemia, an entity rarely described. The child presented with feeding intolerance, poor growth and developmental delay. He was noted to have macrocytic anemia, a markedly low serum vitamin B₁₂ level, and elevated homocysteine and methylmalonic acid levels. Antibodies to intrinsic factor were positive. The mother was healthy, with normal vitamin B₁₂ status. Therapy with vitamin B₁₂ supplements led to excellent recovery of symptoms. Vitamin B₁₂ deficiency should be considered in children presenting with failure to thrive, especially when compounded with neurological symptoms. Early diagnosis and adequate treatment is essential to avoid serious complications.