Rise in plasma trimethyllysine levels in humans after oral lysine load.

Oral administration of 5 g of lysine to healthy male volunteers produced a marked and progressive rise in plasma trimethyllysine (TML) from 3 to 24 h after the lysine load. Urinary TML did not register a similar rise. Plasma and urinary carnitine also increased after the lysine load. A similar rise in TML or carnitine was not seen after a 5 g tryptophan load. This suggests that the effect is specific for lysine and is not a nonspecific consequence of amino acid load.