ALBUMIN AND FIBRINOGEN SYNTHESES INCREASE WHILE MUSCLE PROTEIN-SYNTHESIS DECREASES IN HEAD-INJURED PATIENTS

The effect of trauma on protein metabolism was investigated in the who le body, muscle, and Liver in severely head-injured patients presentin g an acute inflammatory response by comparison to fed control subjects receiving a similar diet. Nonoxidative leucine disposal(an index of w hole body protein synthesis) and muscle, albumin, and fibrinogen synth esis were determined by means of a primed, continuous infusion of L-[1 -C-13]leucine. Nonoxidative leucine disposal increased by 28% in the p atients (P < 0.02). Fractional muscle protein synthesis rate decreased by 50% (P < 0.01) after injury. Fractional and absolute fribrinogen s ynthesis rates were multiplied by two and nine, respectively, after in jury (P < 0.001). Albumin levels piers lower in patients (25.2 +/- 1.2 g/l, means +/- SE) than in controls (33.7 +/- 1.2 g/l, P < 0.001). ho wever, fractional albumin synthesis rates were increased by 60% in pat ients (11.4 +/- 1.0%/day) compared with controls (7.3 +/- 0.4%/day, P < 0.01). Therefore, 1) head trauma induces opposite and large changes of protein synthesis in muscle and acute-phase hepatic proteins, proba bly mediated by cytokines, glucocorticoids, and other stress hormones, and 2) in these patients, hypoalbuminemia is not due to a depressed a lbumin synthesis.