RELATIONSHIP BETWEEN WHOLE-BODY PROTEIN-TURNOVER AND SERUM CREATININEIN CHRONICALLY UREMIC PATIENTS

To investigate the relationship between decline in renal function and alterations of protein metabolism we determined the rate of whole-body protein turnover in a group of 15 postabsorptive chronically uremic p atients (9 males and 6 females) with different levels of serum creatin ine concentrations (average 5.7 +/- 0.4 (SE) mg . dl(-1); range 3.3-9. 1). Patients' age and body mass index were 53 +/- 4 years (range 26-73 ) and 24.7 +/- 0.6 kg/m(2) (range 20.3-28.7), respectively. Nutritiona l status (plasma albumin 3.6 +/- 0.4 g . dl(-1)) and acid-base equilib rium (arterial pH 7.38 +/- 0.01) were fairly controlled by therapy. Wh ole-body leucine rate of appearance (Ra), an index of whole-body prote in turnover, was assessed using a stable isotope technique. L-[1-C-13] leucine was continuously infused and plasma [1-C-13]alpha-ketoisocapro ic acid enrichment was determined in steady-state conditions as a mark er of the intracellular leucine enrichment. The average leucine Ra was 2.03 +/- 0.13 mu mol . kg(-1) . min(-1) (range 1.29-3.19). Using simp le linear regression analysis, the coefficient of correlation between the individual values of serum creatinine concentration and leucine Pa was 0.59 (n = 15; p = 0.02). Leucine Pa did not significantly correla te with blood pH or plasma albumin. In conclusion, we found a positive linear relationship between the values of plasma creatinine concentra tion and the rate of whole-body protein degradation. This correlation suggests that the progression of renal insufficiency is associated wit h accelerated rates of turnover of body proteins.