Liver function test (LFT); hepatic function test; liver function panel (LFP); Alb, Tbil, Dbil, Alk Phos, ALT, Tot Protein
This group of tests measures specific proteins and enzymes in your blood.
Your liver is the second largest organ in your body. It converts the food you eat into energy and nutrients and filters waste from your blood.
A liver panel checks the health of your liver and can help diagnose liver damage or disease. The panel consists of these tests:
Albumin. Albumin is a protein made in the liver.
Alkaline phosphatase (ALP). ALP is an enzyme found in high quantities in your liver, bile duct, and elsewhere in your body.
Alanine transaminase (ALT). ALT is another enzyme found in your liver.
Aspartate transaminase (AST). AST is another enzyme found in your liver, heart, and muscles.
Total protein. Total protein measures the amount of protein in your blood. Globulin and albumin are the two main proteins found in the blood.
Liver panel or liver function tests also measure bilirubin, a waste product that forms when red blood cells break down. This test measures total bilirubin and direct bilirubin. Total bilirubin is the amount of bilirubin in your blood. Direct bilirubin measures the bilirubin that is made in your liver.
You may have this test as part of a routine checkup. You may also have this test if you have symptoms of liver disease or damage. Symptoms include:
Jaundice, or yellow discoloration of your skin and the whites of your eyes
Light-colored or black and bloody bowel movements
Nausea or vomiting
Loss of appetite
Abdominal swelling or pain
Weight loss or gain
You also might have this test if you've been exposed to a hepatitis virus, have a family history of liver disease, drink excessive amounts of alcohol, or take mediations that can cause liver damage.
You may also need this test to help your doctor watch the progression of a virus like hepatitis that affects the liver or liver damage caused by alcohol.
Your doctor may also order these tests:
Gamma-glutamyl transpeptidase (GGT). GGT is another enzyme found in large amounts in your liver, bile ducts, and pancreas.
Prothrombin time. Prothrombin is protein made in your liver. It helps blood to clot. A prothrombin time test measures how long it takes your blood to clot.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Normal ranges for liver function tests vary depending on various factors, including your age and gender.
Results are given in grams per deciliter (g/dL), milligrams per deciliter (mg/dL), units per liter (U/L), or international units per liter (IU/L). Normal findings for adults are:
Albumin: 3.5 to 5 g/dL
Total bilirubin: 0.3 to 1.0 mg/dL
Direct bilirubin: 0.1 to 0.3 mg/dL
ALP: 30 to 120 U/L
ALT: 4 to 36 IU/L
AST: 0 to 35 U/L
Total protein: 6.4 to 8.3 g/dL
High levels of these proteins and enzymes may mean that your liver or bile duct is damaged or diseased. Overall, a pattern of abnormalities among the results may be more significant than the individual test results. But levels of ALT are useful for finding out whether you have hepatitis.
Diseases unrelated to the liver can cause abnormal test results. Some people with advanced liver disease may have normal test results.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Your results can be affected by:
You don't need to prepare for this test. But the test may be more accurate if you fast for 10 to 12 hours beforehand. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.