Normal liver enzyme ranges for aspartate aminotransferase, or AST, are between 10 and 40 units per liter, while normal ranges for alanine aminotransferase, or ALT, are between 7 and 56 units per liter, according to eMedicineHealth. AST and ALT are enzymes used to detect injury or damage to the liver.
Doctors consider mild elevations to be two or three times the normal range, while severe elevations can be thousands of times higher, notes eMedicineHealth. In general, doctors order liver blood tests to determine the cause of abdominal pain or to rule out or confirm suspected liver disease. Doctors order most liver blood tests in unison with kidney function tests and electrolyte levels.