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Table 2 Typical etiologies of nonhepatic hyperammonemia

From: Recurrent noncirrhotic hyperammonemia causing acute metabolic encephalopathy in a patient with a continent ileocecal pouch: a case report

Increased ammonia production

Decreased ammonia clearance

Infections by urea-producing bacteria: Proteus mirablis, Klebsiella species, Escherichia coli, Morganella morganii, Providencia rettgeri, diphtheroids, Mycobacterium genavense, herpes simplex

Ureterosigmoidostomy

Hematooncological disorders: multiple myeloma, chemotherapy for acute leukemia, bone marrow transplantation, 5-fluorouracil

Portosystemic shunts; congenital intrahepatic and extrahepatic

Organ transplantation

Drug-induced: valproic acid, glycine, carbamazepine, ribavirin, sulfadiazine with pyrimethamine, salicylate

Protein load and increased catabolism: severe exercise, seizures, starvation or trauma, total parenteral nutrition, gastrointestinal bleeding, steroid use

Inborn errors of metabolism: urea-cycle disorders, defects in β-oxidation of fatty acids, organic acidemias, disorders of pyruvate metabolism