A person’s liver function test results can indicate the health of the liver and help doctors detect liver damage or disease. Liver function tests measure the level of certain enzymes and proteins in the blood. Some liver function tests indicate damage if they are higher than normal, while other test results will show a lower than normal level if there is damage to the liver. These tests can also help a doctor monitor the side effects of medications that affect the liver. Diseases like cirrhosis or hepatitis can affect liver function test results.
Alanine transaminase (ALT) is a liver function test that measures the levels of an enzyme found in the liver. If the liver is damaged or diseased, this enzyme is released, increasing the level of the enzyme in the blood. Normal liver function test results for ALT fall between 7 and 55 units per liter (U/L).
Similar to ALT, the aspartate transaminase (AST) liver test measures another type of enzyme found in the liver. The levels of this enzyme are increased if there is damage to the liver, or if a person is suffering from liver disease. Normal AST liver function results are 8 to 48 U/L. Higher results on this test indicate liver problems.
Another liver function test that measures enzymes is the alkaline phosphatase test (ALP). Levels of ALP are elevated in the case of liver disease or dysfunction. Normally, ALP levels are 45 to 115 U/L, and if these or other liver function test results are abnormal, a person should consult a physician.
In addition to enzymes, liver function tests can also measure proteins. Albumin tests measure a type of protein made by the liver to help the body function correctly. If this test result is lower than usual, it may indicate liver damage or disease. Normal albumin test levels are 3.5 to 5 grams per deciliter (g/dL).
Total protein is another liver test that measures proteins produced by the liver. Normally, the total protein levels should be between 6.3 and 7.9 g/dL. If these levels are low, it may indicate problems with the liver.
A bilirubin test is another liver function assessment that measures the amount of bilirubin in either the blood or urine. Bilirubin is a type of chemical left behind when red blood cells break down. In a healthy body, bilirubin passes through the liver and is excreted. High levels of bilirubin can indicate liver damage or disease. Normal levels of bilirubin are between 0.1 and 1 milligrams per deciliter (mg/dL).
