Alanine Aminotransferase is an enzyme normally present in the liver. It catalyzes the transfer of an amino group from alanine to a-ketoglutarate, to produce pyruvate, which in turn, is an important contributor to the citric acid cycle. ALT is also present in small amounts in the kidneys, heart, muscles, and pancreas. This test is usually performed to see if the liver is damaged or diseased, since liver damage would result in the release of ALT into the bloodstream. VERY HIGH levels of ALT may be caused by: Recent or severe liver damage (such as viral hepatitis), lead poisoning, drug reactions, exposure to carbon tetrachloride, or decay of a large tumor (necrosis). MILDLY OR MODERATLEY HIGH levels may be caused by: Mononucleosis, hepatitis, or alcohol abuse. SLIGHTLY HIGH levels may be caused by fatty deposits in the liver, use of medicines (statins, antibiotics, chemotherapy, aspirin), or chronic diseases that affect the liver, such as cirrhosis.