L-carnitine in inborn errors of metabolism: what is the evidence?

A questionnaire was posted on the electronic mailing-list Metab-1 to determine current practice as regards the use of oral L-carnitine in medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, propionic acidaemia (PA) and methylmalonic acidaemia (MMA). Thirty-one centres replied: L-carnitine was used routinely by 94% of respondents in PA and MMA but by only 36% in MCAD deficiency. A search was made for published papers on the use of L-carnitine in organic acidaemias and in MCAD deficiency. The quality of evidence to support the use of L-carnitine was graded according to the scale published by the Scottish Intercollegiate Guideline Network. No high-quality evidence was identified.