Elimination of Amino Acids in Acute Renal Failure

Plasma amino acid concentrations and the elimination of parenterally administered amino acids were investigated in 12 patients with nonhypercatabolic acute renal failure. A distinctive plasma amino acid pattern could be observed: plasma concentrations of phenylalanine and methionine were increased, those of valine and leucine decreased. Of the nonessential amino acids, cystine, taurine und tyrosine had elevated but none of them reduced plasma concentrations. The elimination of amino acids was evaluated in a monocompartment model after bolus injection of an amino acid solution containing essential and nonessential amino acids. Pharmacokinetic parameters of 17 amino acids were calculated. The mean elimination half-time was raised by 25%. The elimination half-time of phenylalanine, methionine, glutamic acid, proline and ornithine was increased. Histidine was the only amino acid with – however insignificantly – accelerated elimination from the intravascular compartment. The total clearance rate and total transfer rate was not altered (107 and 97% of normal, respectively). The clearance of threonine, lysine, serine, glycine and histidine was increased, of valine, phenylalanine, glutamic acid and to a minor degree of methionine was decreased. The transfer rate of methionine, lysine, glycine was elevated, of valine, aspartic acid, glutamic acid and ornithine reduced. The demonstration of these pronounced alterations of amino acid elimination in acute renal failure may have major consequences in parenteral amino acid therapy.