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. 2001 Nov;77(913):717–722. doi: 10.1136/pmj.77.913.717

Non-hepatic hyperammonaemia: an important, potentially reversible cause of encephalopathy

N Hawkes 1, G Thomas 1, A Jurewicz 1, O Williams 1, C Hillier 1, I McQueen 1, G Shortland 1
PMCID: PMC1742166  PMID: 11677282

Abstract

The clinical syndrome of encephalopathy is most often encountered in the context of decompensated liver disease and the diagnosis is usually clear cut. Non-hepatic causes of encephalopathy are rarer and tend to present to a wide range of medical specialties with variable and episodic symptoms. Delay can result in the development of potentially life threatening complications, 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 diagnosis. In addition to adequate supportive care, investigation of the underlying cause of the hyperammonaemia is essential and its reversal, where possible, will often result in complete recovery. Detection of an unborn error of metabolism should lead to the initiation of appropriate maintenance therapy and genetic counselling.


Keywords: hyperammonaemia; encephalopathy; portosystemic venous shunt; urea cycle defect

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