Urinary excretion of amino acids in patients receiving intravenous hyperalimentation

Urinary outputs of amino acids in nine patients receiving intravenous hyperalimentation were estimated for evaluating adequacy of dosage and composition of the infusage for the maintenance of normal metabolism of tissue proteins in the subjects. The daily outputs of the methylated amino acids (3-methylhistidine, epsilon-N-methylated lysines and guanidino-N-methylated arginines), which are thought to be derived from tissue proteins, remained in the normal ranges, suggesting that the normal metabolism of tissue proteins was sustained during intravenous hyperalimentation. Relatively large urinary excretion of threonine, serine and glycine might reflect the large dosage of glucose in the infusate and disuse of these amino acids during the treatment, especially in the patients with hepatic dysfunction. Diurnal rhythms in urinary outputs of amino acids in patients receiving intravenous hyperalimentation were not observed, except for the outputs of threonine, serine and glycine, which were large during the 3.00-9.00 h and 15.00-21.00 h periods. The absence of daily fluctuations of the methylated amino acids in urine suggested that there were no diurnal rhythms in the metabolism of tissue proteins in the subjects.