Transient symptomatic zinc deficiency in an exclusively breastfed infant

A 3-month-old, full term female infant, adequate for gestational age, and exclusively breastfed, was admitted with a 10 day history of generalised scaling erythematous dermatitis, affecting the face (perinasal, nasolabial folds and periauricular), acral and intertriginous areas, with irritability and failure to thrive. Her mother had been treated with isoniazid since the third trimester because of family contact with tuberculosis. Based on a diagnosis of suspected impetiginised eczema, the infant was treated with flucloxacillin and prednisolone, and maternal isoniazid was suspended, with no improvement. Investigations found low serum zinc levels in the infant (33 μg/dL; normal range (NR) >60 μg/dL), normal plasma zinc levels in the mother (111.3 μg/dL; NR 68–120 μg/dL) and lower than the normal range of zinc levels in breast milk (270μg/L; NR 1000–2500 μg/L), suggesting acrodermatitis caused by zinc deficiency. Oral zinc supplementation (3 mg/kg/day) was started with a marked improvement in skin lesions, as well as good weight gain. At the age of 6 months, after food diversification, supplementation was suspended, without any recurrence of symptoms.