Quick Look

Blood tests called liver function tests identify the cause of symptoms and track liver disease or damage. These tests measure enzyme and protein levels in the blood. Some assess the liver’s ability to produce protein and eliminate bilirubin, a blood waste product. Others measure enzymes released by liver cells due to damage or disease. Abnormal results don’t necessarily indicate liver disease. Your healthcare provider will usually interpret and explain your results.

What are liver function tests?

Blood tests, known as liver function tests (LFT), measure various substances produced by your liver. These measurements provide crucial information to your healthcare provider about your liver’s overall health and its functioning. A liver panel often assesses multiple substances in a single blood sample, including enzymes, proteins, and byproducts.

Other Names

Liver Profile

Hepatic function panel

Liver function panel

Liver Panel

Why it’s done

Liver function tests are useful for:

• Screening for liver infections, like hepatitis.
• Monitoring diseases such as viral or alcoholic hepatitis, and assessing treatment effectiveness.
• Searching for signs of serious conditions, specifically liver scarring (cirrhosis).
• Monitoring potential side effects of medications.

Common Liver Function Tests

Here are some common liver function tests:

• Alanine transaminase (ALT): This enzyme, found in the liver, helps convert proteins into energy for liver cells. Elevated ALT levels in the bloodstream indicate liver damage, also known as SGPT.
• Aspartate transaminase (AST): AST is an enzyme aiding in amino acid breakdown. Present at low levels in the blood, increased AST may suggest liver or muscle damage, sometimes referred to as SGOT.
• Alkaline phosphatase (ALP): This enzyme, present in the liver and bones, plays a role in protein breakdown. Higher ALP levels may indicate liver damage, blocked bile ducts, or certain bone diseases.

• Albumin and total protein: Albumin, a liver-produced protein, is vital for various bodily functions. Reduced levels may indicate liver damage or disease, as well as other gastrointestinal or kidney-related conditions.
• Bilirubin: Produced during red blood cell breakdown, bilirubin passes through the liver. Elevated levels may signal liver damage or disease, and can also result from conditions like liver duct blockage or certain types of anemia.
• Gamma-glutamyltransferase (GGT): This blood enzyme’s increased levels may suggest liver or bile duct damage, though it is nonspecific and can be elevated in conditions other than liver disease.
• L-lactate dehydrogenase (LD): Found in the liver, higher LD levels may indicate liver damage, but other conditions can also cause elevated LD.
• Prothrombin time (PT): PT measures blood clotting time. Increased PT may indicate liver damage, but it can also be higher due to certain blood-thinning drugs like warfarin.

Bilirubin test

Preparing for the Test

The results of your liver function tests can be influenced by specific foods and medications. Your doctor will likely instruct you to refrain from eating and taking certain medicines before your blood is drawn.

Results

The normal ranges for liver function tests can vary based on factors such as sex, body size, and laboratory standards. On average, the normal ranges are:

• Alanine transaminase (ALT): 0 to 45 IU/L.
• Aspartate transaminase (AST): 0 to 35 IU/L.
• Alkaline phosphatase (ALP): 30 to 120 IU/L.
• Gamma-glutamyltransferase (GGT): 0 to 30 IU/L.
• Bilirubin: 2 to 17 micromoles/L.
• Prothrombin time (PT): 10.9 to 12.5 seconds.
• Albumin: 40 to 60 g/L.
• Total proteins: 3 to 8.0 g/dL.

It’s important to note that these values are general averages, and specific reference ranges may vary between different laboratories. Your healthcare provider will interpret your results based on their knowledge of your individual health and the specific reference ranges used by the laboratory conducting the tests.

References:

1. (2023). Retrieved from https://www.mayoclinic.org/tests-procedures/liver-function-tests/about/pac-20394595 
2. (N.d.). Retrieved from https://www.mayocliniclabs.com/test-catalog/overview/113633 
3. professional, C. C. medical.(n.d.). Retrieved from https://my.clevelandclinic.org/health/diagnostics/17662-liver-function-tests