Liver Function Tests

Test Overview

Some blood tests are used to determine whether your liver is damaged or inflamed. Although these tests help your doctor evaluate how well your liver is working, they cannot tell if you have hepatitis C.

Tests that assess liver function

Your doctor may do tests to measure certain chemicals produced by the liver. These tests can help your doctor check how well your liver is working.

Tests may measure:

• Bilirubin.
• Albumin.
• Total serum protein.

Tests that check for inflammation of the liver (liver enzyme studies)

Your liver may be damaged if you have increased levels of:

• Alanine aminotransferase (ALT or SGPT).
• Aspartate aminotransferase (AST or SGOT).

An increased level of alkaline phosphatase (AP) may indicate blockage of bile ducts.

Why It Is Done

Liver tests are done when a medical history or physical exam suggests that something may be wrong with your liver.

These tests can also help diagnose infections. For instance, when liver enzymes are high, tests may be done to see if you have hepatitis.

If you are taking certain medicines, you may have liver tests to check that the medicine is working or that it is not harming your liver.

How To Prepare

In general, there's nothing you have to do before this test, unless your doctor tells you to.

How It Is Done

A health professional uses a needle to take a blood sample, usually from the arm.

Results

Normal

All levels are within the normal range.

Abnormal

One or more levels are outside the normal range. Abnormal liver function tests may mean that your liver is inflamed or is not working normally. This can be a sign that you have a viral infection.