Impairment of lipid emulsion metabolism associated with carnitine insufficiency in premature infants.

Carnitine status and its relation to lipid metabolism were determined in 11 premature infants (less than 34 weeks of gestation) receiving parenteral nutrition. Intravenous administration of lipid emulsion increased serum concentrations of free fatty acids at 2, 4, and 8 h after infusion. Despite this increase, serum levels of ketone bodies remained low, reaching only 40 to 45% of levels in full-term infants receiving enteral feeds. In premature infants, levels of plasma total and free carnitine were about half those in full-term infants and were not altered by lipid infusion. The results indicate limited potential for lipid emulsion as a source of energy in premature infants, possibly because carnitine insufficiency restricts fatty acid oxidation.