A Liver function test helps determine liver health by measuring the levels of a protein, liver enzyme, or bilirubin in your blood.
Liver function tests are often done in the following situations:
- To look for liver infections, such as hepatitis C
- To monitor the side effects of certain medications that affect the liver,
- To measure liver damage (cirrhosis),
- If you are experiencing symptoms of a liver disorder
- If you are planning to become pregnant.
What is a Liver Function Test?
There are many tests that can be done on the liver, but most of them do not check all liver functions.
Commonly used tests to test liver function are alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), albumin, and bilirubin tests.
ALT and AST tests measure enzymes that are released by the liver to indicate disease or damage. Albumin and bilirubin tests determine how well albumin (a protein) builds up and eliminates bilirubin (bilirubin is a waste product of the blood).
Abnormal results of any liver function test do not mean that you have liver disease or damage. Talk to your doctor about the results of your liver function tests.
Liver function tests (LFT) are used to measure specific enzymes and proteins in human blood. Depending on the test, having higher or lower levels of these enzymes or proteins than normal can indicate a liver problem.
Some common liver function tests include:
1. Alanine Transaminase (ALT) Test
Alanine Transaminase is used by the human body to metabolize protein. If the liver is damaged or not functioning properly, ALT is released into the blood, and this causes the ALT level to rise.
High results of this test can be a sign of liver damage. According to the Mayo Clinic, the normal range for ALT is 7–55 units per liter (U/L). A low level of ALT does not indicate any health problems.
| Test Name | Reference Range |
|---|---|
| Alanine Transaminase | 7 – 55 (U/L) |
2. Aspartate Aminotransferase (AST) Test
Aspartate aminotransferase (AST) is an enzyme found in many parts of your body, including the heart, liver, and muscles. Since AST levels are not a specific cause of liver damage, it is usually measured in conjunction with ALT to check for liver problems.
| Test Name | Reference Range |
|---|---|
| Aspartate Aminotransferase | 8-48 (U/L) |
Doctors can use an ALT-to-AST ratio to help with the diagnosis. When the liver is damaged, AST is released into the bloodstream. A high result of an AST test may indicate a liver or muscle problem. The normal range for AST is 8-48 (U/L). A low level of AST does not indicate any health problems.
3. Alkaline Phosphatase (ALP) Test
Alkaline phosphatase (ALP) is an enzyme found in your bones, bile ducts, and liver. An ALP test is usually done in conjunction with several other tests. High levels of ALP can indicate liver damage, blockage of the bile ducts, or bone disease.
Children and adolescents may have increased ALP levels because their bones are growing. ALP levels can also increase in pregnancy. The normal range for ALP is 45-115 U/L.
| Test Name | Reference Range |
|---|---|
| Alkaline Phosphatase | 45-115 U/L |
Low levels of ALP can occur after a blood transfusion or heart bypass surgery. Low ALP can also result from a variety of conditions, including zinc deficiency, malnutrition, and Wilson’s disease.
4. Albumin Test
Albumin is the major protein made by the liver. It also performs many important bodily functions like:
- Blocking fluid from blood vessels
- Providing nutrition to the tissues.
- Circulating hormones, vitamins, and other substances in the body.
The albumin test measures how well your liver is making this particular protein. A low result of this test indicates that your liver is not working properly. The normal range for albumin is 3.5–5.0 grams per deciliter (g/dL).
| Test Name | Reference Range |
|---|---|
| Albumin Test | 3.5–5.0 (g/dL) |
5. Bilirubin Test
Bilirubin is a waste product in the body that is produced by the breakdown of red blood cells. It is usually processed by the liver. It passes through the liver before being excreted with your stool.
| Test Name | Reference Range |
|---|---|
| Bilirubin Test | 0.1-1.2 (mg/dL) |
A damaged liver can not process bilirubin properly. This leads to abnormally high levels of bilirubin in the blood. A high level of bilirubin test results indicates that the liver is not working properly. The normal range for bilirubin is 0.1-1.2 milligrams per deciliter (mg/dL).
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What is the purpose of the LFT Test?
Liver tests can help determine whether your liver is working properly or not.
The liver performs many important bodily functions, such as:
- Removal of contaminants from the blood
- Converting nutrients from the foods you eat
- Store minerals and vitaminsRegulate blood clotting
- Manufacture of proteins, enzymes and bile
- Remove bacteria from the blood
- Processing substances that can harm your body
- Maintain hormone balance
Before Liver Function Test
Your doctor will give you complete information about how to prepare a blood sample for the test. Certain medications and foods can also affect the levels of these enzymes and proteins in the blood.
Your doctor may ask you to avoid certain types of medicines or they may also ask you not to eat anything for a period of time before the test.
You can wear a sleeveless shirt that can be easily folded while taking a blood sample.
During Liver Function Test
A blood sample is given at a hospital or specialist testing facility for the following tests:
- The skin is cleaned prior to the test, to remove the micro-organisms located on the skin and to avoid contamination of the test sample.
- Possibly a tight bandage is wrapped around the arm, so that the veins emerge and are easier to access. A needle is inserted into the skin to take the sample.
- After the blood is drawn, a bandage or cotton swab is placed over the needle site. And the blood extracted for the sample is sent to the laboratory for examination.
After Liver Function Test
You can usually go about your daily activities after the test. However, if you feel dizzy or heaviness in the head while taking the blood, you should take some rest after the test.
The results of these tests may not tell the doctor exactly the condition that you have or the extent of the damage to the liver. But these can help the doctor take the next steps.
In general, if your test results indicate a problem with your liver function, your doctor will look at your medications and your past medical history to determine the cause. People who drink alcohol, have to stop consuming alcohol to get the test done.
The doctor may do tests to check for hepatitis. They evaluate the liver for fibrosis or fatty liver disease, for which, they may also choose to perform certain imaging tests, such as an ultrasound or CT scan.
What are the risks of LFT Test?
Taking a blood sample for the test is a normal and routine procedure and rarely causes any serious side effects.
However, giving a blood sample is likely to have the following problems:
- Bleeding under the skin
- Excessive bleeding
- Fainting
- Infection
What do liver function test results mean?
Different LFTs provide different information about your liver function. Although not every test result reflects a specific liver condition, their combined result may indicate some kind of liver damage.
LFT can give the following results:
Normal – If the test result is normal then you do not need any other test.
Abnormal – If there is anything abnormal in the result then it becomes necessary to know the exact reason for such changes. Additional tests may be needed to determine the underlying cause.
| Liver Function Test | Normal Range |
|---|---|
| Bilirubin – Total | 0.1 – 1.2 mg/dl |
| Bilirubin – Direct | 0.1 – 0.3 mg/dl |
| Bilirubin -Indirect | 0.2 – 0.8 mg/dl |
| SGPT | 5 – 40 IU/L |
| SGOT | 8 – 37 IU/L |
| Alkaline Phosphatase | 64 – 36 U/L |
| Serum Amylase | 9 – 99 units/100ml |
| Serum lipase | 0 – 110 IU/L |
However, sometimes the result of LFT can be affected due to some kind of problem in the bones or other parts of the body. Not only this, even if there are no symptoms, the result can be abnormal. It would be a good idea to consult a doctor for the correct diagnosis.
Liver function Test Price / cost
Liver function test price may vary lab to lab located in the different-different cities. However, the cost of the Liver function Test (LFT) is Rs. 550 in most of the cities in India.