Non-hepatic hyperammonaemia: an important, potentially reversible cause ofencephalopathy

The clinical syndrome of encephalopathy is most often encountered in the co ntext of decompensated liver disease and the diagnosis is usually clear cut . Non-hepatic causes of encephalopathy are rarer and tend to present to a w ide range of medical specialties with variable and episodic symptoms. Delay can result in the development of potentially life threatening complication s, such as seizures and coma. Early recognition is vital. A history of similar episodes or clinical risk factors and early assessment of blood ammonia levels help establish the dia gnosis. In addition to adequate supportive care, investigation of the under lying cause of the hyperammonaemia is essential and its reversal, where pos sible, will often result in complete recovery. Detection of an unborn error of metabolism should lead to the initiation of appropriate maintenance the rapy and genetic counselling.