Types Primary vs. secondary * Primary<unk>  is caused by several inborn errors of metabolism that are characterised by reduced activity of any of the enzymes in the urea cycle. The most common example is ornithine transcarbamylase deficiency, which is inherited in an X-linked fashion. * Secondary<unk>  is caused by inborn errors of intermediary metabolism, which are characterised by reduced activity of enzymes that are not part of the urea cycle or dysfunction of cells that make major contributions to metabolism. Examples of the former are propionic acidemia and methylmalonic acidemia, and examples of the latter are acute liver failure and hepatic cirrhosis with liver failure. Acquired vs. congenital *Acquired<unk>  is usually caused by diseases that result in either acute liver failure, such as overwhelming hepatitis B or exposure to hepatotoxins, or cirrhosis of the liver with chronic liver failure. Chronic hepatitis B, chronic hepatitis C, and excessive alcohol consumption are common causes of cirrhosis. The physiologic consequences of cirrhosis include shunting of blood from the liver to the inferior vena cava, resulting in decreased filtration of blood and removal of nitrogen-containing toxins by the liver, and then<unk> . This type of<unk>  can be treated with antibiotics to kill the bacteria that initially produce the ammonia, though this doesn't work as well as the removal of protein from the colon prior to its digestion to ammonia, achieved by lactulose administration for frequent (3-4 per day) bowel movements. * Medication-induced<unk>  can occur with valproic acid overdose, and is due to a deficiency in carnitine. Its treatment is carnitine replacement. *Urinary tract infection caused by urease-producing organisms (Proteus species, Pseudomonas aeruginosa, Klebsiella species, Morganella morganii, and Corynebacterium species) can also lead to<unk> . But there are case reports where<unk>  was caused by urease negative organisms. Urease producers form ammonia and carbon dioxide from urea. Ammonia then enters the systemic circulation (most venous supply of the bladder bypasses portal circulation) and enters the blood-brain barrier causing encephalopathy. *Severe dehydration and small intestinal bacterial overgrowth can also lead to acquired<unk> . *Glycine toxicity causes<unk> , which manifests as CNS symptoms and nausea. Transient blindness can also occur. *Congenital<unk>  is usually due to genetic defects in one of the enzymes of the urea cycle, such as ornithine transcarbamylase deficiency, which leads to lower production of urea from ammonia. Specific types The following list includes such examples: * -<unk>  due to ornithine transcarbamylase deficiency * - hyperinsulinism-hyperammonemia syndrome (glutamate dehydrogenase 1) * - hyperornithinemia-hyperammonemia-homocitrullinuria * -<unk>  due to N-acetylglutamate synthetase deficiency * -<unk>  due to carbamoyl phosphate synthetase I deficiency (carbamoyl phosphate synthetase I) * - hyperlysinuria with<unk>  (genetics unknown) * Methylmalonic acidemia * Isovaleric acidemia * Propionic acidemia * Carnitine palmitoyltransferase II deficiency * Transient<unk>  of the newborn, specifically in the preterm
Hyperammonemia
Lactic acidosis
Organic acidemia
Hypermethioninemia
Hyperaemia
Hypouricemia
Isovaleric acidemia
Ketosis