Carnitine excretion: a catabolic index of injury

In patients with trauma or sepsis, carnitine is known to be produced to a greater extent; deficient production could impair the energy management that is required in such patients. To clarify the requirements of carnitine after injury, we studied carnitine elimination (in 10 critically ill injured patients) both during fasting and early parenteral nutrition. Increased carnitine (mainly, free) output after injury (9.36 +/- 1.63 mumol/kg p less than 0.02 vs reference) was negatively related to nitrogen balance (p less than 0.05) and positively to 3-methyl-histidine output (p less than 0.01), acting as a market of body mass catabolism. The output of both total and free carnitine progressively decreased (p less than 0.01) throughout the course of total parenteral nutrition. In conclusion, our data definitively suggest that carnitine loss after injury reflects body cell mass wastage and does not necessarily mean an increased need.