Liver Function Test: Purpose, Types, and What to Expect

A liver function test is a test that checks the levels of certain enzymes and proteins in your blood. Some tests look for enzymes that may only be present in your blood when your liver is damaged or diseased. Others inspect the organ to ensure it is functioning as it should. The liver carries out numerous vital functions necessary for maintaining overall health.

Food is broken down in the digestive system, and this process helps provide nutrients and clean the blood. Proteins are made from amino acids, and this process helps provide energy and store fat. If something goes wrong with it, you may experience yellow skin, slurred speech, and problems with movement. That’s when you might need a liver test.

Why is a Liver Function Test Done?

Liver function tests are done to check whether the liver is functioning correctly. You may have this test to check for liver disease, such as hepatitis. If you have taken the test and it shows that you have the disease, you will need to go to the doctor to seek treatment immediately. Common symptoms of liver problems include:

• Loss of appetite
• Nausea or vomiting
• Weakness or feeling very tired
• Yellowing of the eyes or skin (jaundice)
• Dark urine or light poop (less common)
• Swelling of the abdomen (less common)

If you are at risk for liver damage or disease, your doctor may order a liver test.

• Drinking a lot of alcohol or having an alcohol use disorder
• Have a family member with liver disease
• Severe obesity, particularly when accompanied by diabetes or high blood pressure
• Taking medicines that can damage the liver
• Have gallbladder disease or anaemia

A liver test can also help your doctor see if your disease worsens or how well your treatment is working.

Types of Liver Tests

Different liver function tests can be used to determine the liver’s health. Some of these tests include liver enzymes, bilirubin levels, and liver function tests for specific types of proteins. Liver function tests measure particular enzymes and proteins in your blood. If you have atypical results on any of your liver tests, it’s usually best to have a follow-up to find out the cause of the atypical results. Even mild elevations in test results can be associated with liver disease. Common liver function tests include checking the levels of certain chemicals in the blood.

Common liver function tests include:

1. Alanine Transaminase (ALT) Test

The Alanine Transaminase (ALT) test is used by your body to break down protein. When the liver is injured or not working properly, ALT may leak into the bloodstream. The increase in ALT levels is due to this. A result higher than the typical result for this test may signify liver damage. Approximately 10% of individuals in the United States are believed to have higher-than-normal ALT levels.

2. Alkaline Phosphatase (ALP) Test

The ALP test is used to determine the level of ALP in a person’s blood. ALP is an enzyme found in your liver, bile ducts, and bones. Elevated liver enzyme levels can occur due to liver disorders, bile duct blockages, or certain bone diseases.

3. The Albumin Test

The albumin test is a test to check your liver’s protein production. The albumin test measures how well your liver is producing this protein.

4. Bilirubin Test

The bilirubin test checks how much bilirubin is present in your blood. Bilirubin is a by-product of the process of breaking down red blood cells. The liver processes it typically. The drug passes through the liver before being excreted through your stool. A damaged liver can’t properly process bilirubin, leading to a yellowing of the skin and eyes. This can lead to an unusually high level of bilirubin in the blood. In addition, some inherited diseases can cause bilirubin levels to rise even when the liver is working normally.

5. Aspartate Transaminase (AST) Test

AST is a type of enzyme that exists within liver cells. High blood levels could be an indication of damage or disease.

6. Gamma-Glutamyltransferase (GGT) Test

High levels of the GGT enzyme may indicate liver or bile duct damage.

7. L-lactate Dehydrogenase (LD) Test

LD levels can rise in cases of liver damage, though other medical conditions may also cause an increase.

8. The Prothrombin Time (PT)

The PT test evaluates the duration your blood requires to form a clot. This test determines the speed at which your blood forms clots. If it lasts long, it could be a sign of liver damage.

Symptoms of Liver Disorder

The symptoms of a liver disorder can vary, but they can often include fatigue, nausea, and anaemia. Problems with the liver can make a person very ill and even life-threatening. Symptoms of liver disease include:

• Weakness
• Tiredness or loss of energy
• Weight loss
• Jaundice (yellow skin and eyes)
• Ascites refers to the abnormal collection of fluid within the abdomen
• Discoloured discharge (dark urine or light-coloured stools)
• Nausea
• Vomit
• Diarrhoea
• Stomach pain
• Unusual or excessive bruising and bleeding

If you show signs of liver disease, your doctor might recommend a liver function test. Liver function tests help track disease progression, evaluate treatment effectiveness, and detect possible medication side effects.

How Should One Get Prepared for a Liver Function Test?

Your doctor will provide detailed guidance on how to prepare for the blood draw portion of the test. Certain foods and medications may influence the levels of enzymes and proteins in your blood. Your doctor might advise you to stop taking specific medications or to fast for a set time before the test. Be sure to keep drinking water before the test. For convenience during a blood draw, wear clothing with loose or short sleeves that allow easy access to your arm. This will make it easier for the expert to collect the sample.

What are the Potential Risks of the Liver Test?

Blood collection is a routine procedure and seldom leads to any serious complications. Still, providing a blood sample may carry minor risks such as:

• Bleeding under the skin or hematoma
• Excessive bleeding
• Fainting

What are a Few Steps Post the Liver Test?

After the test, you can usually resume your daily activities. If you feel faint or lightheaded when you have your blood drawn, you should rest before leaving the testing facility. These tests may not determine your exact condition or the severity of liver damage, but they may help your doctor determine the next steps. The doctor will call you to let you know your test results or schedule a follow-up appointment to discuss them. When liver function results show abnormalities, your doctor will examine your health background and any medicines you take to determine the reason. For example, if you drink alcohol frequently, you need to stop drinking it. If your doctor finds that a medicine is causing elevated liver enzymes, they will advise you to stop taking the medication.