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Classification & external resources
ICD-10 E72.2
ICD-9 270.6
DiseasesDB 20468
eMedicine neuro/162  ped/1057
MeSH D022124

Hyperammonemia (or 'hyperammonaemia') is a metabolic disturbance characterised by an excess of ammonia in the blood. It is a dangerous condition that may lead to encephalopathy and death. It may be primary or secondary.

Ammonia is a substance that contains nitrogen. It is a product of the catabolism of protein. It is converted to the less toxic substance urea prior to excretion in urine by the kidneys. The metabolic pathways that synthesise urea are located first in the mitochondria and then into the cytosol. The process is known as the urea cycle, which comprises several enzymes acting in sequence.



Primary vs. secondary

Specific types

In all cases Hyperammonemia results from defects of the Urea cycle. The following list includes such examples:

  • Online 'Mendelian Inheritance in Man' (OMIM) 311250 - hyperammonemia due to ornithine transcarbamylase deficiency
  • Online 'Mendelian Inheritance in Man' (OMIM) 606762 - hyperinsulinism-hyperammonemia syndrome (glutamate dehydrogenase 1)
  • Online 'Mendelian Inheritance in Man' (OMIM) 238970 - hyperornithinemia-hyperammonemia-homocitrullinuria syndrome (ornithine translocase)
  • Online 'Mendelian Inheritance in Man' (OMIM) 237310 - hyperammonemia due to N-acetylglutamate synthetase deficiency
  • Online 'Mendelian Inheritance in Man' (OMIM) 237300 - hyperammonemia due to carbamoyl phosphate synthetase i deficiency (carbamoyl phosphate synthase I)
  • Online 'Mendelian Inheritance in Man' (OMIM) 238750 - hyperlysinuria with hyperammonemia (genetics unknown)


Hyperammonemia is one of the metabolic derangements that contribute to hepatic encephalopathy.

See also

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hyperammonemia". A list of authors is available in Wikipedia.
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