Intracellular amino acids in uremia.

Uremia is characterized by a specific intracellular amino acid (AA) pattern in muscle, which is not consistently reflected by that in plasma. Our results with different AA formulas indicate that abnormal intracellular AA concentrations can be corrected by nutritional therapy that adjusts for the specific AA abnormalities of uremia. Normalization of the intracellular free AA pools may be associated with improved nitrogen utilization. This implies that uremic patients require EAA in other proportions than those needed by normal man. Determination of intracellular free AA in muscle tissue obtained by needle biopsy technique is a valuable tool in tailoring AA supplement to uremic patients. Based on the above observations, our tentative recommendations would be that in patients treated with a low-protein diet, this should be supplemented with an EAA mixture containing tyrosine and with increased proportion of valine and decreased proportion of leucine as compared to those recommended for normal man. The nutritional effect of supplementation with valine should be studied in patients on hemodialysis, in whom reduced valine pools were found in spite of a protein intake of 1 g/kg/day.