Systemic Carnitine Deficiency — A Treatable Inherited Lipid-Storage Disease Presenting as Reye's Syndrome

A 3 1/2-year-old boy presented at three months of age with an acute episode of lethargy, somnolence, hypoglycemia, hepatomegaly, and cardiomegaly, which responded poorly to restoration of the blood sugar level to normal. The absence of ketonuria during subsequent episodes of severe hypoglycemia prompted a search for a defect in fatty acid oxidation. Plasma carnitine (2.0 to 5.0 μmol per liter), muscle carnitine (0.01 to 0.02 μmol per gram, wet weight) and liver carnitine (0.021 to 0.065 μmol per gram, wet weight) were all less than 5 per cent of the normal mean. During a 36-hour fast, ketones were barely detectable. Prolonged treatment with oral carnitine over a six-month period resulted in increased muscle strength, a dramatic reduction in cardiac size, relief of cardiomyopathy, partial repletion of carnitine levels in plasma and muscle, and complete repletion in the liver. Systemic carnitine deficiency is an easily treatable cause of recurrent Reye's-like syndrome. Its diagnosis requires measurement of carnitine levels. (N Engl J Med. 1980; 303:1389–94.) SINCE its description by Engel and Angelini in 1973, carnitine deficiency has emerged as the leading cause of Type I lipid-storage myopathy. In some instances, the disorder appears to be largely limited to skeletal muscle and carries a favorable prognosis.123456 In others, the disorder is generalized, with carnitine levels reduced in plasma and liver as well as muscle.789101112 This form, called systemic carnitine deficiency, carries a less favorable outlook, and a number of fatal cases have been reported. Some cases cannot be easily classified into one or the other category, usually because too few studies have been carried out.13,14 There. © 1980, Massachusetts Medical Society. All rights reserved.