Ketogenic response to fasting in human carnitine deficiencies.

Carnitine and its short-chain and long-chain esters have been determined in muscle and liver of two patients with carnitine-deficient myopathy. Plasma carnitines and ketone bodies were monitored in the two patients during a 38-h fast. The two patients showed different ketogenic responses to the fast. One patient, with carnitine deficiency restricted to skeletal muscle, had exaggerated ketone production on fasting. The other patient, with carnitine deficiency in skeletal muscle and liver, had poor ketone body production on fasting. It is assumed that the presence of adequate levels of carnitine in the liver are crucial for the activation of ketogenic machinery in liver.