Megaloblastic and macrocytic anaemia: Case

This infant has severe vitamin B12 deficiency acquired from the marginal stores of a strict vegan mother through exclusive breastfeeding. The macrocytic anaemia with oval macrocytes and hypersegmented neutrophils establishes the megaloblastic picture, the low serum B12 with both methylmalonic acid and homocysteine raised confirms B12 rather than folate deficiency, and the developmental regression with the tremor marks the neurological involvement that decides the urgency and the replacement schedule. ^[1][8]

Clinical findings and assessment

The key findings are the macrocytic anaemia with the hypersegmented neutrophils, the mild thrombocytopenia of the pancytopenia of impaired DNA synthesis, and the neurological signs of developmental regression and tremor. The raised lactate dehydrogenase with a normal haptoglobin reflects the ineffective erythropoiesis of the megaloblastic marrow, in which the red cell precursors die in the marrow and release their enzymes, rather than a haemolysis that would lower the haptoglobin. ^[1][5]

The history establishes the cause. The infant is exclusively breastfed, and the mother is a strict vegan, so the marginal maternal stores are the only source for the rapidly growing infant, and the supply is depleted within months. The neurological examination documents the lost head control, the coarse tremor, and the hypotonia, and the developmental screen records milestones infant has lost, because the severity and the duration of the deficit at presentation predict the completeness of the recovery. ^[9]