Metabolic Changes in a Patient of Methylmalonic Aciduria Treated with D, L-Carnitine Supplement

Abstract

Carnitine metabolism in a patient with methylmalonic aciduria was investigated. The patient showed a low level of free carnitine and a slightly increased level of acylcarnitine in her serum and urine. After carnitine therapy, acylcarnitine excretion in the urine increased markedly, and the patient had a favorable body weight gain. A small dose of valine was administered with or without the carnitine supplement. This induced metabolic changes, e.g., hypoglycemia and hyperketonemia, with little changes in lactate, pyruvate and ammonia levels. The level of free carnitine in the serum decreased gradually and acylcarnitine was increased by valine administration. These metabolic changes were not much different with or without carnitine supplement. Natural protein tolerance was then investigated. The patient could not tolerate 1.5mg/kg/day of natural protein because of nausea, vomiting, and body weight loss without carnitine. Although nausea and loss of apetite were also seen under carnitine therapy, vomiting did not occur when the patient received 1.5mg/kg/day of natural protein. These results show the usefulness of carnitine for the management of methylmalonic aciduria with restriction of natural protein.