Carnitine in adolescents

Abstract

Carnitine, abundant in muscle and other tissues, is normally synthesized from lysine. Its major metabolic role is transport of long-chain fatty acids into muscle where β oxidation takes place. Normative data are available for carnitine levels, but few studies define carnitine of specific age groups. This report provides data on normal male and female adolescents in relationship to age and pubertal status. The population consisted of adolescents between 10 and 18 years, seen either for routine health maintenance or minor illnesses. Concentrations of carnitine in plasma were determined by radioisotype enzyme assay. The overall mean was 45.3 ± 8.9 μmol/L for free carnitine. There was a trend of decreasing free carnitine with increasing Tanner stage. Among the females, there was a statistically significant correlation with both age and Tanner stage. In contrast, the data for males indicated no statistically significant correlation. The data provided standards for the evaluation of carnitine status in normal adolescents. Total carnitine in plasma ranged from 43.2 to 55.9 μmol/L and was virtually all free carnitine. The significant negative correlation of concentration of free carnitine with age and pubertal stage in females was interesting, although not of clinical importance. It suggests the possibility of female hormonal influence associated with puberty.