Clinical results of long-term treatment with a low protein diet and a new amino acid preparation in patients with chronic uremia.

15 patients with severe uremia (mean serum creatinine concentration 965, range 568-1383 mumoles/l) were treated with an unselected protein restricted (16-20 g protein/day) diet and a new amino acid preparation, containing the essential amino acids in proportions which differed from those recommended by Rose for normal man and which contained in addition histidine and tyrosine, for an average period of 224 (range 33-737) days. Plasma urea concentration decreased and the uremic symptoms disappeared. Ten nitrogen balance studies were performed in 6 patients after a mean treatment time of 151 days. The mean nitrogen balance, corrected for changes in total urea pool, was + 0.4 +/- 0.22 g N/day. In 4 patients, in whom progression of the renal insufficiency was assessed by plots of the reciprocal of serum creatinine concentration versus time, retardation of progression was observed after institution of the regimen. The results show that nitrogen equilibrium can be maintained during long-term treatment with this regimen and suggest that better nitrogen utilization is achieved with the new amino acid preparation than when essential amino acids are given to uremic patients in the proportions considered optimal for normal man. It is further shown that the progression of renal insufficiency may be retarded by this regimen.