Nitrogen balance of uremic patients receiving branched-chain ketoacids and the hydroxy-analogue of methionine as substitutes for the respective amino acids.

The efficacy of the D,L-alpha-hydroxy analogue of methionine and the alpha-keto analogues of valine, leucine and isoleucine as substitutes for the corresponding amino acids was tested by measuring the nitrogen balance of chronic uremic patients receiving glycine as their source of nitrogen while eating a virtually protein-free diet. Calcium salts of the following essential amino acid analogues: 2.01 g D,L-2-hydroxy-4-methylthiobutyrate, 2.70 g 2-oxoisovalerate, 3.80 g of 2-oxoisocaproate, and 2.73 g of 2-oxo-3-methylvalerate, plus the remaining five essential amino acids were given to five patients daily for 5--7 days. Nitrogen balance, corrected for urea accumulation (but not for unmeasured cutaneous losses of nitrogen) averaged +1.24+/- 0.39 g/day. We conclude that this mixture and dosage of amino acid analogues can meet the dietary requirements of chronic uremic patients for methionine, valine, leucine and isoleucine.