Liver enzymes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase are markers of hepatic injury, not hepatic function, and should be referred to as liver chemistries. Albumin, bilirubin, and prothrombin time are direct measures of hepatocellular synthetic function and are appropriately characterized as “liver function tests.” Liver enzymes may be abnormal even in patients without liver disease. The differential for elevated enzymes is broad with many potential causative factors and should be further defined by the patient’s medical history and risk factors.1
Almost all medications are associated with at least a small risk of elevated liver chemistries with or without hepatotoxicity.2 Oral iron supplementation at typical replacement doses has little or no adverse effects on the liver or serum enzyme elevations. However, in high doses or overdoses, it can cause acute hepatotoxicity as a result of iron poisoning. Toxicity occurs after ingestion of ≥3 g of ferrous sulfate (approximately 10 tablets). Severe toxicity with aminotransferases greater than 25 times the upper limit of normal typically occurs with larger overdoses and high initial serum iron levels (>1000 ug/dL). Mild to moderate cases of iron poisoning are usually self-limiting and resolve with supportive care, whereas severe cases become fatal rapidly.3
1. Approach to the Patient with Abnormal Liver Biochemical and Function Tests. UptoDate.com website. https://www.uptodate.com/contents/approach-to-the-patient-with-abnormal-liver-biochemical-and-function-tests. Accessed April 2, 2019.
2. Cohen SM, Kwo PY, Lim, JK. ACG clinical guideline: evaluation of abnormal liver chemistries. Am J Gastroenterol 2017;112:18-35
3. Iron. National Institute of Health website. https://livertox.nih.gov/Iron.htm. Accessed April 3, 2019.