Liver Enzymes and Liver Function Tests and Results

Liver Enzyme Tests Explained

Row of test tube with blood samples
Science Photo Library - Tek Image/Brand X Pictures/Getty Images

Liver Enzyme and Function Blood Test Results

Liver enzymes, or liver (hepatic) function tests, are common blood tests used to determine if the liver is functioning normally or if it has an injury or disease. These tests are drawn from a vein in a doctor’s office, or if you are hospitalized and a special IV is available it can be drawn from that line without a needle stick.

The liver enzyme test results are typically used together, not individually, to diagnose a liver problem.

If the tests indicate a problem, a liver biopsy may be necessary to confirm the test results. Results can be elevated by many prescription medications and some over the counter drugs and supplements.  

For some patients, these lab tests are part of routine monitoring if they are taking a medication known to cause liver problems. 

AST (Aspartate Phosphatase) Lab Results

This test is typically used to detect a liver injury or an active or chronic liver problem. The heart can also release AST, so it is important to look at the entire set of liver tests, rather than just this one test. AST levels can be dramatically affected by shock, low blood pressure or any other condition that deprives the liver of blood and oxygen.

Normal Level:

Male: 8-46 units/liter

Female: 7-34 units/liter

ALT (Alanine Aminotransferase) Lab Results

This test is used to detect liver injuries and long-term liver disease. Highly elevated levels may indicate active hepatitis from any cause, including virus, alcohol, drug or toxin.

Some prescription and over-the-counter medications can cause an increase in ALT levels. ALT levels can be dramatically affected by shock, low blood pressure or any other condition that deprives the liver of blood and oxygen.

Normal level: 5-40 units per liter of blood serum

ALP (Alk Phos, Alkaline Phosphatase) Lab Results

ALP is a substance found in the bile ducts of the liver.

Damage or obstruction of the bile ducts may result in elevated levels of ALP.

Normal Level: 13-39 units/liter

Total Bilirubin (T. Bili) Lab Results

This lab test measure the total amount of bilirubin in the blood, including direct and indirect bilirubin. Bilirubin is produced during the normal process of blood cells dying and the liver excretes bilirubin through bile. Too much bilirubin in the blood results in the patient looking yellow, or jaundiced. This test may detect elevated levels of bilirubin before jaundice is present.

Normal Level: 1mg per 100 ml

Indirect Bilirubin (I. Bili) Lab Results

Indirect bilirubin does not dissolve in water. In order to dissolve in water, and be eliminated from the body, it must go to the liver where it is made into direct (water soluble) bilirubin.

Indirect Bilirubin = Total Bilirubin – Direct Bilirubin

Direct Bilirubin (D. Bili) Lab Results

Direct bilirubin has been converted into a water soluble form of bilirubin by the liver. The proportion of indirect bili to direct bili may change if the liver has difficulty converting indirect into direct.

Normal Level: .4 mg per 100 ml

Albumin Lab Results

Albumin is a protein made by the liver that is very common in blood plasma, which can be measured in the blood.

If the liver has chronic or acute damage, the level of albumin in the blood will typically be low. A low level of albumin can also be caused by poor nutrition.

Normal Level: 3.5-5 grams/100 ml

Common Tests Before and After Surgery


Liver Function Test. The American Association of Clinical Chemistry

Ehren Meyers, RN. RNotes-Nurse’s Clinical Pocket Guide. 2008.

Continue Reading