Liver Function Tests

Liver function tests (also called a liver panel) use a sample of your blood to measure several substances made by your liver. The most common liver function tests measure: Albumin, a protein made in the liver.; Total protein. This test measures the total amount of protein in your blood, which includes albumin and globulins.

These proteins are mainly made in your liver.; ALP (alkaline phosphatase), ALT (alanine transaminase), AST (aspartate aminotransferase), and GGT (gamma-glutamyl transferase). These are enzymes that are mainly made in your liver. Enzymes are proteins that speed up certain chemical reactions in your body.; Bilirubin, a waste product your body makes when it breaks down old red blood cells.

Your liver removes most of the bilirubin from your body.; Lactate dehydrogenase (LDH), an enzyme found in most of the tissues in your body, but some of the largest amounts are found in your liver.; Prothrombin time (PT), how long it takes your blood to clot. Prothrombin is a protein involved in blood clotting. It's made in your liver.; Some of these tests can show how well your liver is working and others can show whether your liver may be damaged by liver disease or injury.

But liver function tests alone usually can't diagnose specific diseases. So, if your results are abnormal, you'll usually need other tests to find the exact cause.

Why this test is done

Many liver function tests are included in a common blood test called a comprehensive metabolic panel (CMP). Your provider often orders a CMP as part of your routine checkup to screen for liver and other diseases.

You may also need liver function tests if you have symptoms of liver disease or damage. These include:

• Nausea and vomiting
• Lack of appetite
• Fatigue
• Weakness
• Jaundice, a condition that causes your skin and eyes to turn yellow
• Swelling and/or pain in your abdomen (belly)
• Swelling in your ankles and legs
• Dark-colored urine (pee) and/or light-colored stool (poop)
• Frequent itching

Even if you don't have symptoms, you may need to be tested if you have a high risk for liver damage. Your risk may be high if you have:

• A family history of liver disease
• Alcohol use disorder (AUD)
• Obesity
• Diabetes
• Been taking certain medicines that may cause liver damage
• Hepatitis or have been exposed to hepatitis (swelling of the liver from infection or injury)

If you already have liver disease, you may need to be tested to monitor your condition and/or to see how well your treatment is working.

How to prepare

Your provider will tell you how to prepare for your test. You will probably need to fast (not eat or drink) for 10-12 hours before the test. Certain medicines can affect your test results, so be sure to tell your provider about everything you take.

But don't stop taking any medicines unless your provider tells you to.

Sample type

Blood

Other names for this test

liver panel, liver function panel, liver profile hepatic function panel, LFT