Liver Tests Explained

Key points

• Symptoms of liver disease can be vague or similar to symptoms of other health problems
• The earlier you’re diagnosed, the better the chance of halting or reversing damage to the liver
• There are lots of tests that your doctor can order to check whether your liver is working properly, or how much damage has been done to the liver
• You might need a liver test if:
  • You have symptoms of liver disease, such as yellow skin and eyes (jaundice) or a swollen belly (ascites)
  • You or your family have had a liver disease before
  • You have a health problem like coeliac disease, type 2 diabetes, obesity, haemochromatosis
  • You drink a lot of alcohol
  • You have taken medicines that could have damaged your liver
  • You are at risk of a virus in your blood, for example if you have used non-sterile equipment to inject drugs, if you have been in close contact with someone who has hepatitis B or if you are unwell after travel to a country with high rates of hepatitis virus infection
• If signs of liver disease are present, tests are needed to find the exact cause of the problem. It may not be possible to diagnose a specific cause of a liver problem in everyone

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Blood tests

Liver tests are blood tests used to help find out the health of your liver and your bile ducts. Your doctor will use these tests along with your history and physical examination to diagnose and manage your liver disease.

Liver tests measure the levels of certain enzymes and proteins in your blood as well as how well the liver is performing its functions. They can also measure enzymes that liver cells release in response to damage or disease.

Abnormal liver test results don’t always indicate liver disease. Your doctor will be able explain your results and what they mean.

Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST)

These are liver enzymes normally found in liver cells. If the liver cells are injured, the enzymes leak out of them into the blood. Raised levels of AST and ALT can indicate liver inflammation. These enzymes are also found in other organs such as the heart and muscles so high levels may not always be due to a liver problem.

In acute injury to the liver, as in viral hepatitis, the level of the ALT and AST may be used to measure the degree of liver inflammation or damage. In chronic liver disease, these enzymes may be entirely within the normal range even if you have cirrhosis (liver scarring).

Albumin

Albumin is the main protein made by the liver. Although there are many reasons that albumin levels may be affected, chronic liver disease causes a decrease in the amount of albumin produced. Low levels of albumin may therefore indicate serious, long standing liver disease. Low levels of albumin may also be because nutrition is poor.

Alkaline phosphatase

This is the most frequently used test to detect blockage (obstruction) in the biliary system. Raised levels of this enzyme may be found in a large number of disorders such as gallstone disease, alcohol-related liver disease, drug-induced inflammation of the liver, primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and bile duct tumours.

Bilirubin

Bilirubin is a yellow pigment formed mainly from the breakdown of a substance haemoglobin in red blood cells. It is taken up from the blood, processed, and then put out into the bile by the liver.

There is normally a small amount of bilirubin in the blood in healthy people (less than 17µmol/L). A damaged liver cannot process bilirubin properly, which leads to high level of this pigment in the blood. Levels greater than 50 µmol/L are usually noticeable as jaundice (yellowing of the skin and eyes).

Gamma-glutamyl transpeptidase (GGT)

Gamma-glutamyl transferase is an enzyme that is throughout the body, but mainly in the liver. It can leak into the bloodstream if the liver is damaged. High levels of GGT in the blood can be a sign of damage to the liver or bile ducts.

Prothrombin Time and INR

The prothrombin time (also called the “protime” or PT) and the INR are tests used to assess the liver’s production of blood clotting factors. Blood clotting factors are proteins made by the liver. When the liver is injured, these proteins are not produced normally. The values for the PT are usually expressed in seconds and compared to a control patient’s blood (normal +/- 2 seconds of control). An INR test is reported as a ratio compared to the result in control patients. In liver disease, abnormal PT or INR do not necessarily mean a high risk of bleeding, and in fact, many people with liver disease are at risk of blood clots.

Other liver tests

Highly specialised tests may be used to diagnose the actual cause of liver disease. Your doctor will request them if required. For example:

• specific antibodies, proteins, and nucleic acids may be used to indicate the presence of viral hepatitis B (HBsAg, HBV DNA) or hepatitis C (anti-HCV antibodies, HCV RNA)
• high levels in the blood of iron, transferrin saturation and ferritin may indicate the presence of hemochromatosis
• low levels of ceruloplasmin are seen in patients with a copper metabolism disorder called Wilson disease
• a low level of alpha-1-antitrypsin may indicate the presence of lung and/or liver disease in children and adults due to alpha-1-antitrypsin deficiency
• immunologic tests such as the antimitochondrial antibody may suggest the presence of primary biliary cholangitis (PBC)
• antinuclear and/or anti-smooth muscle antibodies may indicate the presence of autoimmune hepatitis

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Scans

Ultrasound

If your doctor suspects liver disease or damage, the first scan they will probably ask for is an ultrasound. An ultrasound uses sound waves to take a picture of the inside of the body. It’s painless and it doesn’t use radiation.

If you have an ultrasound, the doctor will look at how the bile ducts and veins are working, and whether the liver is the expected size and shape. An ultrasound will also show other features such as the size of the spleen and whether there is abnormal fluid in the belly.

Magnetic Resonance Imaging (MRI)

An MRI scan uses a strong magnetic field, radio waves and a computer to take a picture of the inside of the body. It’s used to take a close look at the internal organs, including the liver, and can show the extent of liver damage.

Computerised Tomography (CT scan)

A CT scan uses X-rays used to produce three dimensional pictures of the inside of the body. You may have a CT scan to check for cancer or internal bleeding, or to guide a biopsy.

Transient elastography (Fibroscan®)

Sometimes tests are done to estimate how stiff the liver has become. Stiffness in the liver indicates scarring.

Fibroscan® is a completely painless technology that uses sound waves to measure stiffness in the liver. It’s done by placing a probe between the ribs on the right hand side of the chest and pushing a button that delivers a vibration into the liver.

Magnetic Resonance Cholangiopancreatography (MRCP)

This is a type of MRI used to look at the bile ducts. It can be used to look for tumours, stones or narrowing of the bile ducts.

Endoscopic retrograde cholangiopancreatography (ERCP)

This is a type of endoscopy procedure combined with X-rays that may used instead of or as well as an MRI. It is done by passing a flexible tube down your throat to put dye into the bile duct where it connects with the upper part of your small intestine. It can be used to provide more information about the liver, pancreas or bile ducts and can be used to treat blockages, stones, tumours or infection.

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Liver biopsy

Liver biopsy is a procedure used to obtain a small amount of liver tissue, which can be examined under a microscope to determine what is causing the liver disease and the degree of fibrosis (scarring) of the liver.

Liver biopsy is often used to diagnose the cause of chronic liver disease where the diagnosis cannot be made another way. In some conditions such as autoimmune hepatitis, then the main reason for a liver biopsy is to confirm the diagnosis and to check how far the disease has progressed. Your doctor may order a liver biopsy to confirm the diagnosis of liver cancer, although this is not essential as often a diagnosis can be made from a CT or MRI scan taken with an injection of dye.

Liver biopsy can also be used after liver transplantation if there are any complications or concerns.

How is a liver biopsy done?

The most common way a liver sample is obtained is by inserting a needle into the liver between the ribs on the right side of the chest for a fraction of a second. This will be done in hospital, and you will be sent home the same day as long as there are no complications.

You will have a local anaesthetic to numb the skin where the needle is inserted. The biopsy is guided by an ultrasound or CT scan. About half of people don’t experience any pain afterwards, while the rest may have some brief pain that may spread to the right shoulder. You will be given pain medication if necessary.

Sometimes liver biopsies are carried out during surgery, through the jugular vein in the right side of the neck or during an endoscopy procedure where a needle is passed from the stomach into the liver using endoscopic ultrasound.

What are the risks of liver biopsy?

Liver biopsy is a very safe procedure. But as with all medical procedures, there are some risks. These include bleeding from where the needle goes in, infection or damage to nearby organs. Your doctor will take every precaution to make sure the risks are as low as possible. If you experience severe pain after a liver biopsy you must let your healthcare team know straight away.

Is there an alternative to a liver biopsy?

A liver biopsy is considered the gold standard for diagnosing liver conditions. The main alternative to liver biopsy is to diagnose your condition based on physical examination, medical history, blood testing and imaging tests.

In some cases, blood testing is quite accurate in giving the doctor the information to diagnose chronic liver disease, while in other circumstances a liver biopsy is needed to assure an accurate diagnosis.

Do liver biopsies ever need to be repeated?

In most cases, a liver biopsy is only done once to confirm a suspected diagnosis of chronic liver disease. Occasionally, liver biopsy is repeated if your symptoms or liver tests change or to assess how well treatment is working.

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What happens after diagnosis?

Depending on the results of your tests, your GP may manage your condition themselves or refer you to a non-GP specialist such as a hepatologist or gastroenterologist.

Many people with uncomplicated liver disease are managed by the GP. The reasons you might need a referral are:

• the cause of your liver problem is not clear
• your tests show the liver’s condition is getting worse
• there are features that suggest cirrhosis
• you may have an uncommon cause of liver disease such as autoimmune hepatitis
• you have viral hepatitis that needs treatment and your GP wants you to see a liver specialist
• there are signs your liver disease is affecting your nervous system (hepatic encephalopathy), causing yellow discolouration (jaundice) or fluid retention
• there are signs you may have liver cancer

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What next?

New to liver disease?

 

Read about different liver diseases

 

Read about living well

 

 

Reviewed November 2022