Urinary copper losses in infants receiving free amino acid solutions.
Plasma amino acids and the 24-h urinary excretion of copper and amino acids were measured in 18 infants receiving 0.4 g N/kg/day as free amino acids as part of a total parenteral nutrition regimen. Urinary copper excretion correlated positively with total excretion of alpha-amino nitrogen, in general, and the excretion of glycine, methionine, histidine, and lysine, in particular. Infants who received FreAmine II as compared to FreAmine III generally had increased plasma concentrations of glycine and methionine and increased urinary excretion of total alpha-amino nitrogen, glycine, methionine, and of copper. Chronic losses of copper in the urine of infants receiving free amino acid solutions may contribute to copper depletion and the development of a copper deficiency syndrome.