Red cell and plasma amino acid concentrations in renal failure

Red cell and plasma amino acid concentrations were measured in nine healthy subjects, nine patients with advanced chronic renal failure, and before and after dialysis in eight patients undergoing maintenance hemodialysis. Blood was obtained after an overnight fast except for postdialysis specimens. In red cells from the chronically uremic patients and in predialysis specimens, there was increased histidine, cystine, glutamic acid, glycine, ornithine, citrulline, taurine, and N tau-methylhistidine, and an increased glycine to serine ratio. Red cell valine, tyrosine, and the ratios of tyrosine to phenylalanine and valine to glycine were decreased in the two groups. Many amino acid levels that were abnormal in red cells were also abnormal in plasma. However, several amino acids were altered in only one of these compartments. Some red cell or plasma amino acid concentrations were abnormal in the uremic or hemodialysis patients but not in both. During hemodialysis, red cell amino acids did not decrease as markedly as did the plasma concentrations. These findings indicate that in chronically uremic and hemodialysis patients there is an abnormal amino acid pattern in both red cells and plasma. Although the altered amino acid patterns in these two compartments have similarities, they are not identical.