Idiopathic hyperammonemia following high-dose chemotherapy.

摘要

The diagnosis of idiopathic hyperammonemia (IH) is made in the presence of elevated serum ammonia, neurological deterioration of no other obvious aetiology, normal liver function tests and normal amino-acid levels, which rule out enzymatic deficiencies of the urea cycle. Pathological features include presence of Alzheimer type II astrocytes in brain and centrilobular microvesicular steatosis. An acquired deficiency of glutamine synthetase of unknown origin has been suggested as a possible mechanism.1 Such deficiency would result in waste nitrogen circulating as ammonia and not being converted to glutamine. Immuno-suppression and/or high-dose cytoreduetive treatment might be responsible for the inactivation of glutamine synthetase.