Blood and urinary amino acids in children receiving total parenteral nutrition.

Plasma concentrations and urinary outputs of amino acids were estimated in nineteen patients receiving intravenous hyperalimentation to evaluate the adequacy of dosage and composition of the infusates for the maintenance of normal blood concentrations of essential amino acids. The use of high concentrations of branched chain amino acids seems to be appropriate for valine and isoleucine but not for leucine. The high concentration of cysteine in the infusates used induces a very high urinary excretion of cysteine and cystine and are ineffective to bring the decreased plasma cystine levels back to normal.