Some causes of low AST: Uremia, vitamin B6 deficiency , metronidazole 


Some causes of a high AST: Viral hepatitis, cytomegalovirus, Epstein-Barr , cholecystitis, acute fatty liver of pregnancy (AFLP), preeclampsia, HELLP syndrome , hyperemesis gravidarum, intrahepatic cholestasis, acute pyelonephritis, many drugs (including heparin, isoniazid, acetaminophen, methyldopa) , myocardial infarction ,  pulmonary emboli, metastasis, Reye's syndrome, alcoholic hepatitis, hypothyroidism,  muscular dystophy, polymyositis, dermatomyositis, trauma, surgery, malignant hyperthermia, trichinosis, hemochromatosis, autoimmune hepatitis, Wilson's disease, or alpha1-antitrypsin deficiency , mushroom poisoning, hemolytic anemia, and  heat stroke.

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PMID: 2066547