Nutritional vitamin B12 deficiency: Two cases detected by routine newborn urinary screening
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 breastfed infants of vitamin B12-depleted mothers. It also demonstrates that urinary methylmalonic acid measurement is a sensitive indicator of tissue vitamin B12 deficiency.
Key wordsVitamin B12 Methylmalonic aciduria Newborn screening Cobalamin
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