Plasmatic carnitine can be low to very low for many transient and acquired reasons. But hereditary carnitine deficiency in cells is a rare autosomal recessive disorder due to defective carnitine transporters. Onset exceptionally occurs after birth with coma or sudden death, but more commonly the first clinical sign is a highly progressive hypokinetic dilated cardiomyopathy that is generally associated with muscular weakness. This last sign may be major and result in proximal myopathy and amyotrophy. Hypoglycemia- and hypoketosis-linked coma or acute hepatic injuries such as Reye's syndrome may occur after periods of fasting or infections. Near-zero total plasmatic carnitine and free carnitine with normal carnitine urinary excretion is highly suggestive of the disorder. Chromatography of organic acids does not reveal any abnormal substance. Diagnosis is confirmed by analysing the oxidation of fatty acids and transportation of radioactively marked carnitine in lymphocytes or cultured fibroblasts. Patients are treated with pharmacological doses of carnitine lifelong (100 à 200 mg/Kg/day taken by thirds or fourths), and results are remarkable. Myocardiopathy almost always regresses in less than one year leaving no sequela.
Last update: March 2004