Hyperammonemia
Ammonia
A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.
Hyperargininemia
A rare autosomal recessive disorder of the urea cycle. It is caused by a deficiency of the hepatic enzyme ARGINASE. Arginine is elevated in the blood and cerebrospinal fluid, and periodic HYPERAMMONEMIA may occur. Disease onset is usually in infancy or early childhood. Clinical manifestations include seizures, microcephaly, progressive mental impairment, hypotonia, ataxia, spastic diplegia, and quadriparesis. (From Hum Genet 1993 Mar;91(1):1-5; Menkes, Textbook of Child Neurology, 5th ed, p51)
Ornithine Carbamoyltransferase Deficiency Disease
An inherited urea cycle disorder associated with deficiency of the enzyme ORNITHINE CARBAMOYLTRANSFERASE, transmitted as an X-linked trait and featuring elevations of amino acids and ammonia in the serum. Clinical features, which are more prominent in males, include seizures, behavioral alterations, episodic vomiting, lethargy, and coma. (Menkes, Textbook of Child Neurology, 5th ed, pp49-50)
Citrullinemia
A group of diseases related to a deficiency of the enzyme ARGININOSUCCINATE SYNTHASE which causes an elevation of serum levels of CITRULLINE. In neonates, clinical manifestations include lethargy, hypotonia, and SEIZURES. Milder forms also occur. Childhood and adult forms may present with recurrent episodes of intermittent weakness, lethargy, ATAXIA, behavioral changes, and DYSARTHRIA. (From Menkes, Textbook of Child Neurology, 5th ed, p49)
Sodium Benzoate
The sodium salt of BENZOIC ACID. It is used as an antifungal preservative in pharmaceutical preparations and foods. It may also be used as a test for liver function.
Urea Cycle Disorders, Inborn
Rare congenital metabolism disorders of the urea cycle. The disorders are due to mutations that result in complete (neonatal onset) or partial (childhood or adult onset) inactivity of an enzyme, involved in the urea cycle. Neonatal onset results in clinical features that include irritability, vomiting, lethargy, seizures, NEONATAL HYPOTONIA; RESPIRATORY ALKALOSIS; HYPERAMMONEMIA; coma, and death. Survivors of the neonatal onset and childhood/adult onset disorders share common risks for ENCEPHALOPATHIES, METABOLIC, INBORN; and RESPIRATORY ALKALOSIS due to HYPERAMMONEMIA.
Argininosuccinic Aciduria
Rare autosomal recessive disorder of the urea cycle which leads to the accumulation of argininosuccinic acid in body fluids and severe HYPERAMMONEMIA. Clinical features of the neonatal onset of the disorder include poor feeding, vomiting, lethargy, seizures, tachypnea, coma, and death. Later onset results in milder set of clinical features including vomiting, failure to thrive, irritability, behavioral problems, or psychomotor retardation. Mutations in the ARGININOSUCCINATE LYASE gene cause the disorder.
Amino Acid Metabolism, Inborn Errors
Carbonic Anhydrase V
A carbonic anhydrase isoenzyme found in MITOCHONDRIA where it provides bicarbonate ions that are components in the urea cycle and in GLUCONEOGENESIS.
Argininosuccinic Acid
This amino acid is formed during the urea cycle from citrulline, aspartate and ATP. This reaction is catalyzed by argininosuccinic acid synthetase.
Methionine Sulfoximine
Hepatic Encephalopathy
A syndrome characterized by central nervous system dysfunction in association with LIVER FAILURE, including portal-systemic shunts. Clinical features include lethargy and CONFUSION (frequently progressing to COMA); ASTERIXIS; NYSTAGMUS, PATHOLOGIC; brisk oculovestibular reflexes; decorticate and decerebrate posturing; MUSCLE SPASTICITY; and bilateral extensor plantar reflexes (see REFLEX, BABINSKI). ELECTROENCEPHALOGRAPHY may demonstrate triphasic waves. (From Adams et al., Principles of Neurology, 6th ed, pp1117-20; Plum & Posner, Diagnosis of Stupor and Coma, 3rd ed, p222-5)
Amino-Acid N-Acetyltransferase
Ornithine Carbamoyltransferase
A urea cycle enzyme that catalyzes the formation of orthophosphate and L-citrulline (CITRULLINE) from CARBAMOYL PHOSPHATE and L-ornithine (ORNITHINE). Deficiency of this enzyme may be transmitted as an X-linked trait. EC 2.1.3.3.
Orotic Acid
Orotic acid, also known as pyrophosphoric acid dihydrate, is a organic compound that plays a role in the biosynthesis of pyrimidines, and elevated levels of orotic acid in urine can indicate certain genetic disorders or liver dysfunction.
Argininosuccinate Synthase
An enzyme of the urea cycle that catalyzes the formation of argininosuccinic acid from citrulline and aspartic acid in the presence of ATP. Absence or deficiency of this enzyme causes the metabolic disease CITRULLINEMIA in humans. EC 6.3.4.5.
Carbamoyl-Phosphate Synthase I Deficiency Disease
A urea cycle disorder manifesting in infancy as lethargy, emesis, seizures, alterations of muscle tone, abnormal eye movements, and an elevation of serum ammonia. The disorder is caused by a reduction in the activity of hepatic mitochondrial CARBAMOYL-PHOSPHATE SYNTHASE (AMMONIA). (Menkes, Textbook of Child Neurology, 5th ed, pp50-1)
Glutamine
A non-essential amino acid present abundantly throughout the body and is involved in many metabolic processes. It is synthesized from GLUTAMIC ACID and AMMONIA. It is the principal carrier of NITROGEN in the body and is an important energy source for many cells.
Benzoic Acid
Citrulline
Citrulline is an α-amino acid, primarily produced in the urea cycle in the liver and found in some dietary proteins, which functions as a vital intermediator in the nitrogen metabolism and vasodilation, and can be supplemented for potential health benefits in improving blood flow, reducing fatigue, and enhancing exercise performance.
Glutamate Dehydrogenase
Lethargy
Reye Syndrome
A form of encephalopathy with fatty infiltration of the LIVER, characterized by brain EDEMA and VOMITING that may rapidly progress to SEIZURES; COMA; and DEATH. It is caused by a generalized loss of mitochondrial function leading to disturbances in fatty acid and CARNITINE metabolism.
Urea
A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.
Glutamate-Ammonia Ligase
Metabolism, Inborn Errors
Portacaval Shunt, Surgical
Carbamoyl-Phosphate Synthase (Ammonia)
An enzyme that catalyzes the formation of carbamoyl phosphate from ATP, carbon dioxide, and ammonia. This enzyme is specific for arginine biosynthesis or the urea cycle. Absence or lack of this enzyme may cause CARBAMOYL-PHOSPHATE SYNTHASE I DEFICIENCY DISEASE. EC 6.3.4.16.
Carnitine
Argininosuccinate Lyase
An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease ARGININOSUCCINIC ACIDURIA in man. EC 4.3.2.1.
Methylmalonic Acid
A malonic acid derivative which is a vital intermediate in the metabolism of fat and protein. Abnormalities in methylmalonic acid metabolism lead to methylmalonic aciduria. This metabolic disease is attributed to a block in the enzymatic conversion of methylmalonyl CoA to succinyl CoA.
Acetates
Malonates
Malonates are organic compounds containing a malonate group, which is a dicarboxylic acid functional group with the structure -OC(CH2COOH)2, and can form salts or esters known as malonates.
Hyperinsulinism
A syndrome with excessively high INSULIN levels in the BLOOD. It may cause HYPOGLYCEMIA. Etiology of hyperinsulinism varies, including hypersecretion of a beta cell tumor (INSULINOMA); autoantibodies against insulin (INSULIN ANTIBODIES); defective insulin receptor (INSULIN RESISTANCE); or overuse of exogenous insulin or HYPOGLYCEMIC AGENTS.
Arginase
A ureahydrolase that catalyzes the hydrolysis of arginine or canavanine to yield L-ornithine (ORNITHINE) and urea. Deficiency of this enzyme causes HYPERARGININEMIA. EC 3.5.3.1.
Liver Failure
Severe inability of the LIVER to perform its normal metabolic functions, as evidenced by severe JAUNDICE and abnormal serum levels of AMMONIA; BILIRUBIN; ALKALINE PHOSPHATASE; ASPARTATE AMINOTRANSFERASE; LACTATE DEHYDROGENASES; and albumin/globulin ratio. (Blakiston's Gould Medical Dictionary, 4th ed)