Carnitine deficiency in lysinuric protein intolerance: lysine-sparing effect of carnitine.

Plasma carnitine deficiency (41% of normal control) was found in a 9 year-old boy with lysinuric protein intolerance. Following oral carnitine administration, the plasma level of lysine as well as carnitine has significantly increased (p less than 0.05). His well-being seemed to have improved on this substitutive remedy. Hitherto unrevealed these findings on LPI indicate that carnitine has a lysine-sparing effect and suggest that there might be a biosynthetic pathway of carnitine directly from free lysine in human.