Abstract
A 15-year-old male was admitted to the hospital because of a disturbance of consciousness. He was in good mental and physical condition until the previous day, when he vomited and experienced a reduction of consciousness. He was brought to the hospital the day followiniug the onset of symptoms. On admission the patient was stuporous. Neurological focal signs were not demonstrated. Computed tomographic (CT) scanning on admission showed no definite abnormality. Cerebrosprinal fluid had no pleocytosis. At this time, Reye's syndrome was suspected because of the acute change of consciousness and the presence of hyperammonemia. The disturbance of consciousness progressed and he became comatose on the day following admission. CT scanning showed that the suprasellar, ambient and quadrigeminal cisterns could almost not be detected and the bilateral ventricles were narrowed. The plasma aminogram demonstrated an elevation of alanine, lysine, glutamine, glutamic acid, aspartate and proline. Ketonuria was negative, but the urinary excretion of orotic acid was markedly increased. This data was indicative of the existence of an ornithine transcarbamylase (OTC) deficiency. The patient was died on the third day after hospitalization. The OTC activity in the liver was 10% of normal. Activities of other enzymes in the urea cycle were within normal limits. It is unusual that the symptoms of the enzyme deficiency occurred, both acutely and late at an adult age, as in this case. This case demonstrates that OTC deficiency should be considered in the differential diagnosis of hyperammonemia of adult onset.
