EFFECTS OF IV GLUCOSE AND ORAL MEDIUM-CHAIN TRIGLYCERIDE IN PATIENTS WITH VLCAD DEFICIENCY

Patients with the adult-onset myopathic form of very-long-chain acyl–coenzyme A dehydrogenase (VLCAD) deficiency are characterized by muscle pain, rhabdomyolysis, and myoglobinuria after prolonged exercise or fasting.^1,2 The residual VLCAD activity in these patients is sufficient to maintain normal oxidation of fat at rest, but fat oxidation does not increase during exercise.³ This probably causes an energy deficit and IM accumulation of fat intermediates that may induce the exercise-induced symptoms.³ Free fatty acids (FFAs) are an important energy source during fasting and prolonged exercise. Patients with VLCAD deficiency have therefore been encouraged to avoid fasting, and have been treated with carbohydrate-rich/low-fat diets or dietary supplements of medium-chain triglyceride (MCT).^1,2 Theoretically, MCT could be beneficial in VLCAD deficiency, because MCT bypasses the metabolic block, and the breakdown products of MCT enter the hepatic portal vein just minutes after ingestion.⁴ These recommendations, however, are based on uncontrolled case reports. In placebo-controlled trials, we studied the effect of IV glucose and MCT on exercise performance in VLCAD deficiency.