Carnitine deficiency syndromes are reviewed from the Departments of Neurology and Pediatrics, Columbia Presbyterian Medical Center, New York, NY. Primary carnitine deficiency is a decrease of intracellular carnitine that impairs fatty acid oxidation and is not associated with another systemic illness. It may be systemic or muscular, presenting as progressive cardiomyopathy, hypoketotic hypoglycemic encephalopathy, or myopathy. Age at onset is 1 month to 7 years, with a mean of 2 years. In encephalopathy, carnitine levels in plasma and tissues are below 10% of normal, and acylcarnitines are proportionately reduced. Acylcarnitine to free carnitine ratio is normal. Treratment is oral carnitine at daily doses of 100 to 200 mg/kg. Intermittent diarrhea and a fishy body odor are described as side effects of carnitine replacement. Muscle carnitine deficiency is characterized by severe reduction in muscle carnitine levels and normal serum carnitine. Secondary carnitine deficiency is manifested by a decrease in levels of plasma or tissue carnitine, and is associated with genetically determined metabolic errors, acquired medical conditions, or iatrogenic factors. Metabolic errors involve fatty acid oxidation, B-oxidation cycle, aminoacidurias, and mitochondrial disorders. Acquired disorders include cirrhosis, malnutrition, vegetarian diet, celiac disease, extreme prematurity, AIDS, and Fanconi syndrome. Anticonvulsant treatment with valproate has been linked to some carnitine deficiencies. Several mechanisms are proposed for valproic acid-induced carnitine deficiency, some involving an underlying primary metabolic inborn error. The authors recommend prophylactic carnitine in all children under 2 years of age who are treated with valproate. Secondary carnitine deficiencies are managed by high carbohydrate, low fat frequent feedings, and vitamin/cofactor supplements (carnitine, glycine, and riboflavin). 
COMMENT. In the same issue, Coulter DL, from the Boston City Hospital, discusses the risk factors and treatment of carnitine deficiency in epilepsy . Carnitine deficiency in epilepsy results from metabolic diseases, poor nutrition, and anticonvulsants, especially but not exclusively valproate. Carnitine supplements benefit high-risk, symptomatic patients and those with free carnitine deficiency, but not the low-risk, asymptomatic patients and those with normal carnitine levels.