Sulphur amino acids in plasma and muscle in patients with chronic renal failure: evidence for taurine depletion.

The sulphur amino acids methionine, cysteine (1/2-cystine) and taurine were determined by ion-exchange chromatography in plasma and muscle biopsy material obtained from 46 patients with chronic renal failure. Twelve patients were untreated, eight patients were treated with a low protein diet supplemented with essential amino acids, 11 patients treated with maintenance haemodialysis and 15 patients with continuous ambulatory peritoneal dialysis (CAPD). Patient data were compared to data obtained from 18 healthy subjects. Plasma cysteine was elevated in the untreated patients, in the patients treated with low protein diet and in the maintenance haemodialysis patients. Muscle methionine was significantly elevated in the CAPD patients. Plasma taurine was decreased in the untreated patients and in the CAPD patients and muscle taurine was borderline low in the untreated patients and significantly decreased in the other patient groups. The results show that taurine depletion may occur in patients with chronic uraemia despite normal or elevated concentrations of precursor sulphur amino acids, suggesting inhibited synthesis or enhanced degradation of taurine in the uraemic state.