Nutritional vitamin B12 deficiency: two cases detected by routine newborn urinary screening

Eur J Pediatr. 1992 Mar;151(3):218-20. doi: 10.1007/BF01954389.


We describe two asymptomatic newborns with nutritional vitamin B12 deficiency in whom increased urinary methylmalonic acid was detected by routine neonatal screening at 3 weeks of age. Both infants were exclusively breast-fed. One mother suffered from pernicious anaemia, and the other was a strict vegetarian. Both mothers had no clinical or haematological abnormality, aside from a borderline mean corpuscular volume for the vegetarian mother. This report illustrates the early appearance of functional vitamin B12 deficiency in breast-fed infants of vitamin B12-depleted mothers. It also demonstrates that urinary methylmalonic acid measurement is a sensitive indicator of tissue vitamin B12 deficiency.

Publication types

  • Case Reports

MeSH terms

  • Breast Feeding
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Methylmalonic Acid / urine*
  • Mothers
  • Neonatal Screening*
  • Vitamin B 12 / therapeutic use
  • Vitamin B 12 Deficiency / diagnosis
  • Vitamin B 12 Deficiency / drug therapy
  • Vitamin B 12 Deficiency / urine*


  • Methylmalonic Acid
  • Vitamin B 12