Primary hyperammonemic disorders (Urea cycle disorders)

Hyperammonemia is a metabolic condition characterized by elevated levels of ammonia in the blood, and may result in irreversible brain damage if not treated early and thoroughly. Hyperammonemia can be classified into primary or secondary hyperammonemias depending on the underlying pathophysiology. Detoxification of ammonia is mainly accomplished by the urea cycle in periportal hepatocytes. If the urea cycle is directly affected by a defect of any of the involved enzymes or transporters, this results in primary hyperammonemia.