Blood tests used to monitor and diagnose liver damage or disease are known as liver function tests (LFT). The levels of certain proteins and enzymes in the blood are measured with the Liver Function test.
How well the liver is getting rid a waste product from the blood called bilirubin and doing its normal job of making protein is measured by some of the liver function tests. Enzymes secreted by the liver cells in response to disease or damage are measured by other liver function tests.
Liver diseases are not always indicated by abnormal liver function tests results. Your liver function tests results and what they mean will be explained to you by your health care provider.
What are LFT (liver function tests)?
Also called liver panels (Liver function tests) are blood tests that measure various proteins, enzymes, and other substances produced by the liver. These liver panel tests checks your overall liver health. Often, in a single blood sample, at the same time, all the different substances are tested.
What are the 6 major liver function tests?
The most usual liver function tests include:
- Albumin, a liver protein.
- Total blood protein. The total amount of blood protein is measured by this test.
- Alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate aminotransferase (AST) and GGT (gamma-glutamyl transferase). These are various enzymes produced by the liver.
- Bilirubin, a waste product from the liver.
- LD (Lactate dehydrogenase), an enzyme seen in most body cells. Lactate dehydrogenase is released into the blood when cells have been damaged by injury or disease.
- PT (Prothrombin time), a blood clotting protein.
It could be an indication of liver disease if the levels of one or more of these substances are out of the normal range.
Other names: liver profile, liver function panel, liver panel, LFT, liver function panel.
Purpose of a liver function test (LFT)
Liver function tests can be used to:
- It measures disease severity, especially cirrhosis (scarring of your liver).
- Monitoring potential side effects of certain drugs.
- To screen for hepatitis and other liver infections.
- To determine the effectiveness of treatment and to monitor the progress of diseases, like alcoholic hepatitis or viral hepatitis.
- Liver function tests accesses the levels of some blood proteins and enzymes.
Why do you require liver function tests?
If you have symptoms of liver disease, you may need liver function tests. This includes:
- Stomachache
- Dark urine
- Light stool
- Fatigue
- Jaundice, yellowing of the eyes and skin.
- Vomiting and nausea
- Diarrhea
If you have certain risk factors, you may equally need the liver panel test. You may be at increased risk of disease of the liver if you:
- You think you have been exposed to viral hepatitis
- You are taking medicines that can cause damage to your liver.
- There is liver disease in your family.
- Addiction to alcohol, a condition that makes it difficult to control how much drinks you take.
Performing a liver panel test
Liver function tests require blood to be drawn from your arm vein. This is a routine procedure that is performed in a hospital, clinic, laboratory, or doctor's office. Though not as comprehensive as a laboratory liver tests, there are some home tests that require a skin prick.
What happens before liver function tests?
Before your liver function test, make plans to fast for up to 12 hours and drink only water during that time. Also, since certain prescription and over-the-counter drugs or supplements can interfere with the test, make sure your doctor is aware of what drugs you are taking. Before performing a liver function tests your health care provider will give you specific guidelines about which medicines to take and how long to avoid others.
Prior preparation is not required for all liver panel tests. For example, for an expanded liver test that you order and go for testing to a laboratory does not require prior fasting. Fasting for 12 to 14 hours is required for a comprehensive liver tests.
To find out if supplements are needed, be sure to read the instructions carefully for an at-home fingerprint liver test.
What happens during the liver function tests?
All that is needed for liver function tests is routine blood draw. Blood is drawn from a vein in the arm into a vial with a small needle and tested in a laboratory. With an antiseptic, the phlebotomist will first clean the area thoroughly. You may feel a sting sensation when they’re inserting or removing the needle. As if you were drawing blood for another medical panel, you may feel some pain or bruising after the test. The whole process takes maximum of five minutes.
Finger pricks are required for home testing. The kit includes a small needle or lancet. You will be given a test strip on which you will use drops of blood and which you will then store in the container provided for shipment to the laboratory. It will take maximum a minute to collect the sample and prepare the dried blood card for the laboratory. Please note that test kit instructions may vary. Therefore, before taking your blood sample, it is important that you read all instructions.
What happens after your liver function tests?
After taking blood for a liver test, there are no restrictions. However, you may feel weak or tired if you fast for 12 to 14 hours before your lab test. You can bring a snack to consume after the test. After the liver function tests you can return to the normal activity. There is little to no recovery instructions other than changing the adhesive bandage.
Liver function tests results and follow-up
Interpreting liver function tests results
You will be provided with different values for the different substances being measured in your blood when you receive your liver function tests results. You can compare high or low values with normal values. The question is what do tests numbers mean? It requires some skill to interpret your liver function tests results. Your doctor will guide you through your results and how to interpret them.
Liver function tests normal range
Between different body sizes and between genders and between different laboratories, the normal range varies. On average, liver function tests normal range is:
- 2 to 17 micromol/l: Bilirubin.
- 10.9 to 12.5 seconds: PT (Prothrombin time).
- 40 to 60 g/L: Albumin.
- 3 to 8.0 g/dl: Total protein.
- 0 to 45 IU/L: ALT (Alanine transaminase).
- 0 to 35 IU/L: AST (Aspartate Transaminase).
- 30 to 120 IU/L: ALP (Alkaline phosphatase).
- 0 to 30 IU/L: GGT (Gamma-glutamyltransferase).
What do elevated ALT and AST mean?
Liver damages can be indicated by high ALT and AST levels. When the liver is under stress, this is the enzyme most frequently released into the bloodstream. If both ALT and AST levels are equally high, this indicates a non-alcoholic damage, which may include toxins or other infections. When AST is twice ALT, it is a sign of an alcohol-related damage.
Are there risks associated to liver function tests?
The risk of blood tests is very low. You may feel bruising or pain at the injection site, but most blood draw symptoms disappear rapidly.
What do liver function tests results mean?
It could mean that your liver not working properly or is damaged, if one or more liver function test results are outside the normal range. A variety of medical conditions can cause damage to your liver, for example:
- Alcoholism (Alcohol use disorders).
- Liver cancer
- Diabetes
- Hepatitis A.
- Hepatitis C.
- Hepatitis B.
Consult your doctor if you have any doubts about your liver function tests results.
A message from Big Man Lab:
One of the easiest ways for your doctor or you can access your liver health is through liver function tests. It only requires a small blood sample to produce a lot of information, whether you're screening for liver disease or just want to test the effects of a treatment or medication. Keep in mind that though liver function tests are highly recommended for liver screening, they may not provide enough information to make a liver diagnosis. But your next steps can be guided with the help of information from your LFT.
