Liver function tests (LFT) are blood tests that are used to aid in the diagnosis and monitoring of liver diseases. It measures the amounts of specific proteins and enzymes in the blood. The normal levels are, ALT - 7 to 55 units per liter, AST - 8 to 48 U/L, ALP - 40 to 129 U/L, total protein - 6.3 to 7.9 g/dL, albumin- 3.5 to 5.0 grams per deciliter, bilirubin - 0.1 to 1.2 milligrams per deciliter, GGT (gamma-glutamyl transferase) - 8 to 61 U/L, LDH - 122 to 222 U/L, and prothrombin time - 9.4 to 12.5 seconds.