Carnitine levels in serum and urine obtained from 136 infants with normal diet were compared with that from 80 infants with carnitine-free diet. The result showed no significant age-related difference in the levels of carnitines. The reference values of serum free, acyl, and total carnitine were 20.2 - 83.4, 15.9 - 54.9, and 46.8 - 119.7 nmol/ml, respectively. Urinary carnitine levels were different between each individuals and the reference values of free, acyl, and total carnitine were 0 - 55.5, 0 - 56.3, and 3.8 - 125.8nmol/m/ respectively. However the free and total carnitine level in serum of the infants with carnitine-free diet were lower than that of the infants with normal diet (p < 0. 01), there was little difference in acyl carnitine level in serum between these two groups. These results suggested that acyl carnitine might have more important roles in human than free carnitine, and were considered to be the reason why the infants with carnitine-free diet didn't suffer from "carnitine deficiency". The carnitine levels of the gastric juice, intestinal juice, and ascitic fluid obtained from 46 specimens were similar to the serum carnitine level of the same individuals. In pediatric surgery, post-operative patients are generally limited to taking exogenous carnitine and lose endogenous carnitine through the loss of gastric juice, intestinal juice and ascitic fluid. The importance ,of carnitine metabolism in pediatric surgery should always be kept in mind.
