Effect of carnitine on lipid metabolism in the neonate. II. Carnitine addition to lipid infusion during prolonged total parenteral nutrition.

The effect of carnitine administration on lipid metabolism and carnitine and acylcarnitine plasma values of newborn infants, given total parenteral nutrition for the first 7 days of life, was studied during a 4-hour infusion of Intralipid. An increase in plasma concentrations of total carnitine, free carnitine, and short-chain and long-chain acylcarnitine was found, but no significant change in triglycerides, free fatty acids, glycerol, or beta-hydroxybutyrate plasma values was noted, as compared with values obtained without carnitine administration. Moreover, the low free carnitine and short-chain and long-chain acylcarnitine plasma levels found in newborn infants after 7 days of total parenteral nutrition did not seem to impair the utilization of infused lipids. The results support the concept that the relation between the carnitine pool and lipid metabolism can be influenced by intravenous glucose infusion. Low carnitine plasma concentrations do not necessarily signify a depletion of body carnitine, and sufficient tissue carnitine concentrations can probably maintain good lipid utilization for an extended period.