Hyperammonemia

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**Hyperammonemia**
*Classification & external resources*

Ammonia
ICD-10	E 72.2
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 non-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.

1 Types
- 1.1 Primary vs. secondary
- 1.2 Specific types
2 Sequelae
3 See also
4 External links

[edit] Types

[edit] Primary vs. secondary

Primary hyperammonemia is caused by several inborn errors of metabolism that are characterised by reduced activity of any of the enzymes in the urea cycle.
Secondary hyperammonemia is caused by inborn errors of intermediary metabolism characterised by reduced activity in enzymes that are not part of the urea cycle (e.g .Propionic acidemia, Methylmalonic acidemia) or dysfunction of cells that make major contributions to metabolism (eg hepatic failure).

[edit] Specific types

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

Mendelian Inheritance in Man (OMIM) 311250 - hyperammonemia due to ornithine transcarbamylase deficiency
Mendelian Inheritance in Man (OMIM) 606762 - hyperinsulinism-hyperammonemia syndrome
Mendelian Inheritance in Man (OMIM) 238970 - hyperornithinemia-hyperammonemia-homocitrullinuria syndrome
Mendelian Inheritance in Man (OMIM) 237310 - hyperammonemia due to N-acetylglutamate synthetase deficiency
Mendelian Inheritance in Man (OMIM) 237300 - hyperammonemia due to carbamoyl phosphate synthetase i deficiency
Mendelian Inheritance in Man (OMIM) 238750 - hyperlysinuria with hyperammonemia

[edit] Sequelae

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

[edit] See also

[edit] External links

Organic Acidemia Association

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v • d • e Metabolic pathology (E70-90)
Amino acid	Phenylketonuria - Alkaptonuria - Ochronosis - Tyrosinemia - Maple syrup urine disease - Propionic acidemia - Methylmalonic acidemia - Isovaleric acidemia - Primary carnitine deficiency - Cystinuria - Cystinosis - Hartnup disease - Homocystinuria - Citrullinemia - Hyperammonemia - Glutaric acidemia type 1
Carbohydrate	Lactose intolerance - Glycogen storage disease (type I, type II, type III, type IV, type V, type VI), Fructose intolerance, Galactosemia
Lipid	Lipid storage disorders Sphingolipidoses: Gangliosidosis - GM2 gangliosidoses (Sandhoff disease, Tay-Sachs disease) - GM1 gangliosidoses - Mucolipidosis type IV - Gaucher's disease - Niemann-Pick disease - Farber disease - Fabry's disease - Metachromatic leukodystrophy - Krabbe disease Neuronal ceroid lipofuscinosis (Batten disease) - Cerebrotendineous xanthomatosis - Cholesteryl ester storage disease (Wolman disease) Hyperlipidemia - Hypercholesterolemia - Familial hypercholesterolemia - Xanthoma - Combined hyperlipidemia - Lecithin cholesterol acyltransferase deficiency - Tangier disease - Abetalipoproteinemia
Mineral	Cu Wilson's disease/Menkes disease - Fe Haemochromatosis - Zn Acrodermatitis enteropathica - PO₄³⁻ Hypophosphatemia/Hypophosphatasia - Mg²⁺ Hypermagnesemia/Hypomagnesemia - Ca²⁺ Hypercalcaemia/Hypocalcaemia/Disorders of calcium metabolism
Fluid, electrolyte and acid-base balance	Electrolyte disturbance - Na⁺ Hypernatremia/Hyponatremia - Acidosis (Metabolic, Respiratory, Lactic) - Alkalosis (Metabolic, Respiratory) - Mixed disorder of acid-base balance - H₂O Dehydration/Hypervolemia - K⁺ Hypokalemia/Hyperkalemia - Cl⁻ Hyperchloremia/Hypochloremia
Porphyrin and bilirubin	Acatalasia - Gilbert's syndrome - Crigler-Najjar syndrome - Dubin-Johnson syndrome - Rotor syndrome - Porphyria (Acute intermittent porphyria, Gunther's disease, Porphyria cutanea tarda, Erythropoietic protoporphyria, Hepatoerythropoietic porphyria, Hereditary coproporphyria, Variegate porphyria)
Glycosaminoglycan	Mucopolysaccharidosis - Hurler syndrome - Hunter syndrome - Sanfilippo syndrome - Morquio syndrome
Glycoprotein	I-cell disease - Pseudo-Hurler polydystrophy - Aspartylglucosaminuria - Fucosidosis - Alpha-mannosidosis - Sialidosis
Other	Alpha 1-antitrypsin deficiency - Cystic fibrosis - Familial Mediterranean fever - Lesch-Nyhan syndrome