PE26.3 | Vitamin B12 Folate Deficiency Anaemia — Summary & Reflection

KEY TAKEAWAYS

Megaloblastic anaemia is caused by impaired DNA synthesis due to B12 or folate deficiency; both produce identical CBC and smear findings (MCV >100 fL, macro-ovalocytes, hypersegmented neutrophils ≥5 lobes or ≥1 with ≥6 lobes). The critical distinction: B12 deficiency additionally causes subacute combined degeneration of the spinal cord (posterior columns + corticospinal tracts) — folate deficiency does NOT cause neurological disease. In India, B12 deficiency in infants is predominantly nutritional: breastfed infants of strict vegetarian/vegan mothers. Folate deficiency occurs with goat's milk feeding, haemolytic anaemias (high folate demand), malabsorption, and antiepileptic drugs. The B12-before-folate rule is absolute: establish B12 status first; giving folate alone corrects the CBC while neurological damage progresses silently. Treatment: B12 deficiency with neuro signs — IM hydroxocobalamin; dietary B12 deficiency without neuro — high-dose oral B12. Folate deficiency — oral folic acid 1–5 mg/day. Monitor with reticulocyte response (3–5 days), Hb rise, and neurological re-assessment.

REFLECT

Return to Kavya's presentation: an 8-month-old infant losing developmental milestones, with a vegan mother who had no idea her breast milk was B12-depleted. At what point could this have been prevented? Antenatally — if the mother had been screened and supplemented. At birth — if B12 supplementation had been recommended for vegan mothers at the postnatal visit. At the 6-week or 3-month check — if the developmental trajectory and maternal diet had been reviewed together. As a paediatrician in primary or secondary care, how would you build a systematic approach to identifying infants at risk of nutritional B12 deficiency before they lose milestones? What would you say to a mother in this situation to explain the urgency without inducing guilt about her dietary choices?