Liver function tests are blood tests used to help diagnose and monitor liver disease or damage. The tests measure the levels of certain enzymes and proteins in your blood.
Some of these tests measure how well the liver is performing its normal functions of producing protein and clearing bilirubin, a blood waste product. Other liver function tests measure enzymes that liver cells release in response to damage or disease.
Conditions other than liver disease or damage can lead to abnormal liver function test results. Test results can be normal in people who have liver disease or damage.
What liver function tests are?
A liver function test is a common blood test. Doctors ask you to have this test to find out how well your liver is working. Sometimes it is purely a routine test. At other times the doctor uses it to find out why you have particular symptoms. A liver function test is actually a series of tests to look for different things within a sample of your blood. This is why they are usually called liver function tests, or LFTs for short.
What the liver does?
The liver is the chemical factory of the body. It performs many important jobs including Storing some digested foods (nutrients) Converting fat to energy when the body needs it Producing bile Making blood proteins Helping the blood to clot Making other chemicals the body needs Breaking down harmful substances A blood test can show problems with these processes, and help the doctor to find out what could be causing the problems.
Why you may have liver function tests?
You may have liver function tests for the following reasons. As part of a general health check when you are first diagnosed with cancer or other illnesses To help diagnose the cause of symptoms, such yellowing of the skin and whites of the eyes (jaundice) Before and after treatment, to check how well your liver is working To check for secondary cancer in the liver, along with other tests such as an ultrasound scan, CT scan or liver biopsy.
Having the test
You can have LFTs done at the GP surgery or hospital. Occasionally you may be asked not to eat anything for a few hours before the test. If you are taking any medicines, you should take them as normal unless you are told otherwise. You may have blood taken for other tests at the same time. For example, you might have a full blood count to check for anaemia. The results should be ready either on the same day or within a few days. How soon you get them depends on how urgent the test is.
What LFTs can show
Liver function tests can show many things. They can give the doctor an idea of which disease may be causing changes in the liver. But they aren’t enough in themselves to make a diagnosis. They are one of a series of tests done to diagnose disease. If you are already diagnosed with a condition, LFTs can be helpful in monitoring your disease or treatment. The doctor can look for a rise or fall in the levels of substances tested, which may indicate damage or improvement to your liver. Below are some of the substances that the doctor may want to look at in your blood. These include enzymes and proteins made by the liver. Alanine aminotransferase (ALT) Aspartate aminotransferase (AST) These are both enzymes that help to process proteins. ALT and AST levels may be raised if your liver is inflamed or injured. Alkaline Phosphatase (ALP) Gamma-Glutamyl transferase (Gamma GT) These are also both enzymes. ALP and GT may be raised when there is a blockage in your liver or bile duct, or if you drink a lot of alcohol.
Bilirubin: Bilirubin is a chemical in bile. High levels in the blood cause jaundice. Bilirubin may be raised when there is a problem with your liver or gallbladder.
Albumin: This is a protein that may be at a low level with some types of cancer. Albumen can also be low if you have not been eating properly and are malnourished. You may also have blood tests called clotting studies. These show if your blood is clotting normally to stop bleeding. Because the liver makes the proteins that are needed for clotting, these tests can help to show up liver problems.
