Liver function tests (hepatic panel)

This page was reviewed under our medical and editorial policy by

Toufic Kachaamy, MD, Chief of Medicine, City of Hope Phoenix

This page was reviewed on May 26, 2023.

In some cases, a doctor may order a blood sample to check the health of the patient's liver. Through liver function tests, the blood is analyzed for an array of liver enzymes, proteins and other substances.

This group of tests is also known as:

  • Liver panel
  • Liver profile hepatic function panel
  • LFT

These laboratory tests can indicate liver problems, possibly caused by cancer or another disease, but they can’t definitively diagnose cancer and are often an indicator of something that needs a workup, rather than being a diagnostic tool on their own.

What the liver function panel analyzes

Liver function tests are typically performed at a lab using a blood draw. The lab test measures several protein indicators, including:

Albumin: Low albumin levels can result from malnutrition, liver disease such as cirrhosis (scarring of the liver), kidney or thyroid disease, or an infection. High albumin levels may signal severe diarrhea or dehydration.

Total protein: As with albumin, low levels of total protein may indicate issues such as liver and kidney disease. High total protein levels may suggest the presence of multiple myeloma (a blood cancer) or infections with viral hepatitis or human immunodeficiency virus (HIV).

Prothrombin time (PT): PT measures how long the plasma (the liquid part of the blood) takes to clot. The liver makes coagulation factors that aid clotting, so slow clotting time (a high PT) may be associated with liver disease or damage.

A liver panel tests blood levels of several enzymes, including:

ALP (alkaline phosphatase): The liver, bones, kidneys and digestive system contain this enzyme, which also occurs in smaller amounts in the rest of the body. Elevated levels may not always be clinically significant, but in some cases may indicate serious diseases such as bone metastases, Hodgkin lymphoma, a bacterial infection or heart failure. A high ALP also may result from mononucleosis (viral infection), a blocked bile duct, bone disorders or liver disease, such as cirrhosis and hepatitis (inflammation of the liver). ALP levels may be higher in children and pregnant women. Some drugs, including birth control, can affect ALP levels.

ALT (alanine transaminase): This enzyme mainly occurs in the liver, and it flows into the blood when liver cells get damaged. ALT levels can reveal a liver problem before symptoms, such as jaundice (a yellowing of the skin and eyes), become noticeable. ALT used to be called SGPT (serum glutamic-pyruvic transaminase).

AST (aspartate aminotransferase): Level changes in AST, an enzyme in the liver and muscles, can help detect or follow liver problems. It’s also called SGOT or serum glutamic oxaloacetic transaminase test.

Gamma-glutamyl transferase: This enzyme is also found mostly in the liver, though it’s present throughout the body. Liver damage causes it to leak into the bloodstream, so high levels may mean the patient has liver disease or a bile duct injury. It’s also called GGT, gamma-glutamyl transpeptidase, gamma-GT, GGTP and GTP.

Lactate dehydrogenase: This enzyme is used throughout the body in energy production. High levels can indicate tissue damage, such as liver or kidney disease, injury to the heart or other muscles, pancreatitis, some infections and some cancers, including lymphoma and leukemia. It’s also known as LD, LDH or lactic acid dehydrogenase.

Bilirubin: A hepatic panel also measures levels of total bilirubin, a waste product. This yellowish substance is part of bile, a digestive juice produced by the liver and stored in the gallbladder before being released into the small intestine. When the liver isn’t working well, bilirubin can build up in the blood and cause jaundice. High levels of bilirubin may signal liver or gallbladder disease, bile blockage, or red blood cell production problems. However, it’s important to check with a doctor, because high bilirubin levels can also be the result of taking certain medications or eating certain foods. With a severe blockage of the bile duct, the stool may become clay-colored, as bilirubin may not be reaching the stool in quantities high enough to turn the stool its normal color.

Other blood tests for the liver

A doctor may order other blood tests along with a liver panel to gather more information on the patient's health. These may include a comprehensive metabolic panel, which looks at some of the same substances as the liver panel, but adds glucose, calcium, sodium, potassium, chloride, carbon dioxide and BUN (blood urea nitrogen).

Total protein measurement in a comprehensive metabolic panel often includes examining the patient's A/G ratio, which compares amounts of the two main forms of protein in the blood, albumin and globulins. A high A/G ratio can indicate the existence of leukemia and some genetic disorders. A low A/G ratio can be a sign of liver or kidney disease or an autoimmune disease.

If a patient has one or more risk factors for liver cancer, his or her doctor may recommend an alpha-fetoprotein tumor marker (AFP) test. It measures a substance produced by cancer cells or normal cells reacting to cancer; the test can signify cancer of the liver, testicles or ovaries. High AFP levels also can indicate hepatitis, cirrhosis or other liver disease.

The care team may also order liver imaging with an ultrasound, CT scan or MRI to look at the liver, the bile duct and gallbladder. A specialized noninvasive test to look for cirrhosis or fibrosis may also be ordered, such as a FibroScan®. Sometimes, a liver biopsy is needed to determine the reason for the abnormal liver tests.

Risk factors for liver cancer:

  • Long-term infection with hepatitis B or C. Hepatitis C is more common in the United States, and it often doesn’t cause symptoms for many years. Hepatitis B usually does initially cause symptoms, such as jaundice and feeling sick, but doesn’t always become a chronic infection for most people.
  • Cirrhosis
  • Non-alcoholic fatty liver disease
  • Long-term alcohol abuse
  • Obesity
  • Smoking
  • Type 2 diabetes
  • Hereditary hemochromatosis (metabolic disease)

What to expect during a hepatic function panel test

There’s no preparation for a liver panel, unless the doctor wants to expand the procedure to include a comprehensive metabolic panel, in which case the patient would need to avoid eating and drinking for eight to 12 hours before the test.

The blood sample may be taken by a phlebotomist, an expert in drawing blood. A small needle is inserted into a vein, usually in one of the patient's arms. A thin plastic tube connects the needle to one or more vacuum test tubes. These are sent to a laboratory for processing and compared to reference ranges.

Risks of liver function tests

The patient may feel discomfort when the phlebotomist inserts the needle into the vein, and the patient may develop a bruise at the needle site.

Benefits of liver function tests

A liver panel may indicate a patient has cancer before he or she experiences symptoms. Liver cancer often doesn’t produce symptoms until it’s advanced beyond early stages. These tests can also be useful for monitoring how the liver cancer is responding to treatment, and if it may be progressing.

Liver function test results

A liver panel can only indicate that a patient may have cancer or another condition. Follow-up testing is usually required.

If test results suggest that a patient has cancer, it could be in the liver or elsewhere in the body. It may be cancer that originated in the liver and bile system, called primary tumors, or spread from another location, called secondary tumors or metastases.

Secondary liver tumors occur more often than primary liver tumors. The most common type of cancer that spreads to the liver is colorectal cancer, followed by breast and pancreatic cancers.

In addition to primary and secondary liver tumors, a liver panel may suggest that a patient has multiple myeloma, lymphoma or leukemia.

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