Myristoyl-L-carnitine-13C3 Hydrochloride is labelled Myristoyl-L-carnitine Hydrochloride (M884745), a long-chain fatty ester of carnitine which is accumulated and released into the circulation, in fatty-acid oxidation defects. Pattern of Lauroyl-L-carnitine can be diagnostic for a number of ß-oxidation defects.