[Urinary excretion of creatinine and 3-methylhistidine in multiply injured patients]

The daily urinary excretion of 3,methylhistidine (3,MeHis) was measured in eight severely injured patients for periods of at least two weeks to at most one month after the trauma. The patients were fed with 0.20 +/- 0.05 g X kg-1 X 24 h-1 of nitrogen and 25 +/- 5 kcal X kg-1 X 24 h-1 given as glucose. The pattern of 3,MeHis and creatinine excretion as well as the weight loss suggested the following: 1) the muscle protein breakdown in these patients was approximately twice the normal value (the mean 3,MeHis excretions were respectively 7.98, 7.21, 6.26 and 5.14 mumol X kg-1 X 24 h-1 for the four week study period, compared with the normal value of 3.73); 2) the creatinine excretion decreased slowly. This showed the magnitude of muscle wasting in these patients who, in one month, could lose up to 20% of their initial weight. Various factors could be responsible for increasing and extending the muscle protein catabolism: the importance of muscle damage, the metabolic response to neurotrauma, sepsis and prolonged immobilization. In these conditions, it would seem useless and even harmful to try, at all costs, to obtain a positive nitrogen balance. The authors suggest therefore an average intake of 0.2 g X kg-1 X 24 h-1 of nitrogen, which should be sufficient to meet the requirements for protein synthesis.