Carnitine insufficiency in children with inborn errors of metabolism: prevalence and treatment efficacy.

BACKGROUND: Carnitine is necessary for the transfer of long-chain fatty acids from the cytosol into mitochondria for subsequent β-oxidation. A carnitine deficiency results in impaired energy production from fatty acids.

METHODS: We reviewed the plasma level of total carnitine, free carnitine, and acylcarnitines in 1270 children with psychomotor retardation, low growth, and weight parameters. Tandem mass spectrometry (MS/MS) was applied. Low free carnitine level in plasma was used as a marker of carnitine deficiency.

RESULTS: A total of 102 (8%) children had free carnitine level <19 μmol/L (norm 19-60 μmol/L). As a result of the subsequent investigation, hereditary diseases were diagnosed in 76 (¾) children and out of that 19 had very low free carnitine plasma level (<10 μmol/L). Fanconi syndrome, fat oxidation defects, primary systemic carnitine deficiency, mitochondrial encephalomyopathy, and Noonan syndrome were revealed in these 19 children.

CONCLUSION: Efficacy of levocarnitine treatment in children with very low free carnitine level differs according to pathogenesis of diseases. The highest efficacy was observed in primary systemic carnitine deficiency.