Methaemoglobinaemia in an Infant with a Cow’s Milk Protein Allergy

Abstract

Methaemoglobinaemia (MetHb) is a functional anaemia that can be life-threatening in severe cases. MetHb in adults and older children usually results from exposure to toxins from ingestion or skin exposure, whereas MetHb in infants under six months old usually occurs due to exposure to well water, severe metabolic acidosis from diarrhoea, or, in rare cases, secondary to cow’s milk protein allergy (CMPA). In this case report, a young infant presented acutely with shock secondary to profuse diarrhoea and MetHb requiring intravenous fluids and methylene blue and was subsequently diagnosed with CMPA. The early recognition and prompt treatment of CMPA may prevent the recurrence of MetHb symptoms and excessive diagnostic testing in this vulnerable population.