Everything You Need to Know About Liver Function Tests

Liver function tests, also called liver chemistries, enable to determine of the health of the liver by measuring the levels of liver enzymes, proteins, and bilirubin present in the blood.

The liver function test is usually recommended in these situations:
  1. to check for the damage from liver infections that include – hepatitis B and hepatitis C
  2. to assess the side effects of some medications that affect the liver
  3. if you are having liver disease, to monitor the disease and how the treatment works
  4. if you have the symptoms of a liver disorder
  5. if you have some medical conditions like diabetes, high blood pressure, anemia or high triglycerides
  6. if you have gallbladder disease
  7. if you drink alcohol heavily
Some tests to check for liver abnormalities consist of the following:
  1. alkaline phosphatase (ALP)
  2. alanine transaminase (ALT)
  3. aspartate aminotransferase (AST)
  4. albumin
  5. bilirubin
The AST and ALT tests calculate enzymes that the liver releases for any disease or damage. The albumin test helps to measure how well the liver creates albumin, while the bilirubin test measures how well it removes bilirubin. ALP can be used to determine the bile duct system of the liver.

If the results are abnormal for any of these tests, then this requires a follow up to know the exact cause of the problem. Also, mildly elevated results are related to liver disease. However, these enzymes are found in other places than the liver.

You may talk to a doctor about the results of the liver function test and what they really mean for you.


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What are common liver function tests?

Liver function tests are mainly used to detect the presence of particular proteins and enzymes in the blood.

Depending on the test you need to perform, either higher- or lower-than-normal levels of these proteins or enzymes will indicate any problem with your liver.

Common liver function tests include:

Alanine transaminase (ALT) test

Alanine transaminase (ALT) is used by the body to metabolize protein. In case the liver is not functioning properly or damaged, then ALT may be released into the blood that causes ALT levels to increase. If the test result is higher than normal, then this may be a sign of liver damage.

If an ALT is more than 25 IU/L in females and 33 IU/L in males, then it requires further testing and assessment.

Aspartate aminotransferase (AST) test

Aspartate aminotransferase (AST) is an enzyme that has been found in different parts of the body such as – heart, muscles, and liver. As AST levels are not specific for liver damage as ALT, it is generally measured together with ALT to check for various liver problems.

If the liver gets damaged, then AST can be released into the bloodstream. Thus, the higher result on an AST test might indicate a problem with the muscles or liver.

The normal range for AST is usually 40 IU/L in the case of adults and might be higher for infants and young children.

Alkaline phosphatase (ALP) test

Alkaline phosphatase (ALP) is said to be an enzyme usually found in the liver, bile ducts and bones. An ALP test is usually ordered together with other tests. Higher levels of ALP might indicate blockage of bile ducts, bone disease or liver inflammation.

Both adolescents and children might have elevated levels of ALP as their bones are growing. Pregnancy can increase the level of ALP. Hence, the normal range for ALP is upto 120 U/L for adults.

Albumin test

Albumin is the protein produced by the liver. It performs several important functions of the body. For example, albumin:
  1. nourishes the tissues
  2. transport vitamins, hormones and other substances throughout the body
  3. stops fluid from coming out of blood vessels
An albumin test evaluates how well the liver produces this protein. If the result is low for this test, then this denotes your liver is not functioning properly.

The normal range for albumin is usually 3.5–5.0 grams each deciliter (g/dL). However, low albumin may be the reason for improper nutrition, infection, inflammation and kidney disease.

Bilirubin test

Bilirubin is actually a waste product from the breakdown of red blood cells that usually gets processed by your liver. It can pass through the liver before being excreted through the stool.

The damaged liver cannot process bilirubin properly which causes a higher level of bilirubin present in the blood. Thus, a high result on a bilirubin test might indicate that the liver is not functioning properly.

The normal range for bilirubin is usually 0.1–1.2 milligrams per deciliter (mg/dL). However, there are some inherited diseases that increase the level of bilirubin but the liver function is normal.

Why do I require to perform a liver function test?

Liver tests help to determine if your liver is working properly. The liver performs several functions of the body such as:
  1. remove contaminants from the blood
  2. convert nutrients from the foods you eat
  3. store vitamins and minerals
  4. regulate clotting of blood
  5. produce cholesterol, enzymes, bile, and proteins
  6. detect factors that fight against infection
  7. remove bacteria from the blood
  8. process substances that may cause harm to the body
  9. maintain the balance of hormone
  10. regulate the level of blood sugar
Some problems with the liver can make a person extremely sick and can be life-threatening, at times.


Symptoms of liver disorder
  1. weakness
  2. weight loss
  3. jaundice (yellow skin and eyes)
  4. fatigue or loss of energy
  5. fluid collection in the abdomen called ascites
  6. discolored bodily discharge such as light stools or dark urine
  7. nausea and vomiting
  8. diarrhea
  9. abdominal pain
  10. irregular bleeding
  11. abnormal bruising
Your doctor might suggest performing a liver function test if you find some symptoms of liver disorder. The different liver function tests can help to assess the progression or treatment of disease and ultimately, test for side effects of some medications.

How to prepare for a liver function test

Your doctor will give detailed instructions on how to prepare for a blood test in London.

There are certain foods and medications that can affect the level of these enzymes and proteins in the blood. Your doctor might ask not to take some medications or even ask not to eat anything for sometime before the test. Make sure you continue drinking water before the test.

You may wear a shirt with sleeves that can be rolled up easily for collecting blood samples.

How a liver function test is performed
  • The healthcare provider will clean your skin before conducting the test to lessen the chances of any microorganisms causing an infection.
  • They will warp an elastic strap on the arm so that veins are more visible. After this, they will use a needle to take blood samples from your arm.
  • After this, the healthcare provider will place a bandage and some gauze over the affected area. Then the blood sample will be sent to the laboratory for further testing.
Risks of a liver function test
  1. Hematoma or bleeding under the skin
  2. fainting
  3. infection
  4. excessive bleeding
What happens after a liver function test

After the test is done, you can leave and continue with your normal life. However, if you are lightheaded or faint during the blood draw, then you should take proper rest before leaving the testing center.

The results of the tests might not tell the doctor about the condition you have or your liver damage but it can help to take the next step. Your doctor will call with the results or discuss them during the follow-up appointment.

In case the results detect any problem with liver functioning, then your doctor will review the medications and check your medical record to determine the exact cause.

If you are addicted to heavy drinking, then make sure you stop quickly. When the doctor detects a particular medication that is causing elevated liver enzymes, then he will advise stop taking the medication.

Your doctor may even ask to test you for hepatitis, full blood test in London, other diseases or infections that can affect the functioning of the liver. They may even choose to do imaging such as a CT scan or an ultrasound. They may suggest a liver biopsy to assess the liver for fibrosis, fatty disease or other conditions.