Body cell mass and leucine metabolism in cirrhosis

To investigate the influence of body composition on leucine metabolism, leucine turnover and oxidation were measured in six patients with stable biopsy-proven cirrhosis and in six age- and gender-matched controls using [1-14C]leucine tracer. Fat-free body mass and body cell mass were estimated from quantified measurements of H2(18)O and bromide dilution. Although there were no differences in body weight, body surface area, body mass index, or fat-free body mass between study groups, body cell mass was decreased in cirrhotic patients (37.6 +/- 0.1 vs. 46.4 +/- 1.8 kg; P less than 0.05). Leucine turnover did not significantly differ between groups in absolute values or when corrected for body weight or fat free body mass. However, cirrhotic patients had accelerated leucine turnover based on body cell mass (171.3 +/- 8.2 vs. 143 +/- 7.6 mumol.kg-1.h-1; P less than 0.03). Plasma leucine levels were decreased in cirrhosis (76.9 +/- 9.7 vs. 117.9 +/- 8.1 mumol/L; P less than 0.001) and correlated with an expanded extracellular water compartment (r = -0.91; P less than 0.001) and leucine oxidation (r = 0.91; P less than 0.01) in the cirrhotic patients but not in the control subjects. These data indicate that body composition and fluid compartments are important factors influencing leucine metabolism in cirrhosis and should be considered in future studies.