Biochemical and physiologic consequences of carnitine palmityltransferase deficiency

A patient with a long history of exercise‐induced pain developed myoglobinuria and respiratory failure following extensive exercise (football). Although muscle histochemistry was normal, tissue oxidation of 14Clabeled palmitate was decreased, and muscle carnitine palmityltransferase (CPT) activity was one‐tenth of normal. During fasting, his creatine kinase (CK) rose from 127 mu/ml to 278 mu/ml and blood ketones failed to exhibit a normal rise. Triglycerides were normal, as was fatty‐acid mobilization. Prolonged exercise resulted in an inordinately increased CK with only moderate elevations in lactate. Treatment with medium‐chain triglycerides did not alter his symptoms or improve exercise performance. Pain on exercise is a common complaint, but the occurrence of myoglobinuria points to a defect of energy metabolism. Screening for defects of fat utilization may be accomplished by the prolonged‐exercise test, invitro oxidation of 14C‐labeled substrates, and prolonged fasting.