The effect of a keto acid-amino acid supplement to a restricted diet on the progression of chronic renal failure.

We treated 24 patients who had chronic renal failure with a low-phosphorus diet containing 20 to 30 g of mixed-quality protein, supplemented by amino acids and their keto analogues. Seventeen patients had well-defined rates of progression before treatment, as assessed by serial determinations of serum creatinine levels. By extrapolating these rates of progression, we found that 10 of the 17 (59 per cent) had a clinically important slower rise in creatinine levels during long-term treatment (average, 20 months) than predicted; none had a faster rise than predicted. Seven of the 17 patients began treatment before creatinine reached the level of 8 mg per deciliter; in six of the seven, followed for an average of 22 months, creatinine has remained at or below the level at the start of treatment. Nutrition, as assessed by body weight, nitrogen balance, serum albumin, and serum transferrin, has been well maintained. This regimen slowed or arrested the rise in creatinine levels and thus must have slowed or halted the progression of renal insufficiency in a majority of cases, especially when treatment was initiated before creatinine had reached the level of 8 mg per deciliter. The mechanism underlying this effect remains to be determined.