Fatty liver and abnormal liver tests: what the results can mean

Liver blood tests are part of many routine health checks, so it is common to receive a report with one or two values marked as high or low. That can be worrying, especially if you feel perfectly well. In many cases the explanation is straightforward, and one of the most frequent findings behind abnormal results is fatty liver disease. This guide explains what liver tests measure, why results can fall outside the reference range, how fatty liver is assessed and what you can do to look after your liver.

What liver function tests measure

A liver function test, sometimes called a liver panel, is a group of blood tests taken from a single sample. It usually includes:

• ALT and AST: enzymes found in liver cells; higher levels can suggest the liver is inflamed or under strain.
• ALP and GGT: enzymes that can rise with problems in the bile ducts, among other causes.
• Bilirubin: a substance produced when old red blood cells are broken down, which the liver normally clears.
• Albumin and total protein: proteins made mainly by the liver, which give clues about how well it is working.
• Prothrombin time: a measure of how quickly blood clots, which depends on proteins the liver makes.

Some panels also include LDH, an enzyme present in many tissues. Doctors look at the pattern across all of these results, together with your symptoms, medicines and risk factors, rather than focusing on a single number.

Preparing for the test

You may be asked not to eat or drink for 10 to 12 hours beforehand, although instructions vary, so follow the guidance your clinic gives you. Tell the team about every medicine and supplement you take, and do not stop any prescribed medicine unless your doctor advises it. The blood draw itself takes only a few minutes.

Why a result can be abnormal

An abnormal liver test is a signal to look more closely, not a diagnosis. Possible explanations include:

• inflammation of the liver (hepatitis), for example from alcohol or an infection
• fat building up in the liver
• a problem with the bile ducts
• an effect of certain medicines on the liver
• reduced liver function from longer-standing liver disease

Just as importantly, abnormal results do not always come from the liver. A recent illness can cause a temporary change, some medicines alter the values, and conditions elsewhere in the body can raise certain markers; a high ALP, for example, can come from bone rather than liver. That is why doctors often repeat the test and may add further investigations before drawing conclusions.

Fatty liver disease: the most common explanation

Non-alcoholic fatty liver disease (NAFLD) is a common condition in which fat builds up in the liver. It is now also known as metabolic dysfunction-associated steatotic liver disease (MASLD), a name that reflects its close link with weight, blood sugar and blood pressure.

You are more likely to develop it if you:

• are overweight, particularly with extra fat around the waist
• have type 2 diabetes or metabolic syndrome
• have high blood pressure or high cholesterol
• have polycystic ovary syndrome
• eat an unbalanced diet or are not very physically active
• are over 50

Fatty liver usually causes no symptoms and is often discovered by chance on a blood test or scan done for another reason. Some people notice tiredness, a general feeling of being unwell or discomfort under the right side of the ribs.

Understanding the stages

Fatty liver disease is described in stages:

1. Simple fatty liver (steatosis): fat has built up but has not damaged the liver.
2. Steatohepatitis (MASH, previously NASH): the fat is accompanied by inflammation, which can progress.
3. Fibrosis: scarring has developed, although the liver usually still works well.
4. Cirrhosis: more severe scarring that affects how the liver works and can cause serious complications.

Most people only ever have the first stage. The aim of assessment is to identify the smaller group who may have inflammation or scarring, because lifestyle changes and closer follow-up can help prevent progression.

Other causes your doctor will consider

Because several conditions can affect liver tests, part of the assessment is ruling out other causes. These include alcohol-related liver disease, viral hepatitis, haemochromatosis (an inherited condition that causes iron build-up) and primary biliary cholangitis, a condition thought to involve the immune system. Your doctor will ask honestly and without judgement about alcohol, because it helps tell fatty liver disease apart from alcohol-related liver disease.

How fatty liver is assessed

Assessment usually combines several steps:

History and examination

Expect questions about your symptoms, medicines, alcohol intake and family history, along with measurements of your height, weight and waist.

Further blood tests

Additional blood tests look for other causes of raised liver enzymes. Routine results can also be combined into scoring systems, such as FIB-4 or APRI, that help identify, or reassure about, significant scarring.

Imaging

An ultrasound scan can show fat in the liver. CT and MRI can do the same, but none of these scans on their own can show inflammation or scarring. Elastography measures how stiff the liver is, which can indicate scarring; it can be done with a special ultrasound technique or with MRI.

Liver biopsy

A small sample of liver tissue examined under a microscope is the only test that can confirm steatohepatitis and show how advanced it is. It is not needed for most people. Doctors generally consider it when other tests suggest advanced scarring or when another liver condition needs to be ruled out.

What helps protect the liver

For most people, lifestyle change is the main treatment. Weight loss is the central recommendation and can reduce liver fat, inflammation and scarring. Practical steps include:

• eating a healthy, balanced diet
• aiming for at least 150 minutes of physical activity a week
• losing weight if you are overweight, with support if you need it
• keeping alcohol low, within no more than 14 units a week
• not smoking

These changes have wider benefits too, lowering the risk of heart disease, chronic kidney disease, high blood pressure and type 2 diabetes. If tests show scarring, a liver specialist can discuss whether any additional treatment is appropriate. For people living with obesity, a specialist may also talk through medical or surgical weight-loss options. If you are at risk of viral hepatitis, ask about hepatitis A and B vaccination.

Follow-up matters. Many people with fatty liver are advised to have a review at least once a year, with further tests every few years, so that any change is picked up early.

When to see a doctor

Speak to a doctor if you have been told your liver tests are abnormal, if you think you may have fatty liver or if you have several of the risk factors above. Most liver conditions cause no symptoms in their early stages, so do not wait to feel unwell. See a doctor promptly if you notice yellowing of the skin or the whites of the eyes (jaundice), persistent itching, constant tiredness and weakness, loss of appetite or unexplained weight loss, as these can be signs of more advanced liver disease.

How a health check-up can help

Because fatty liver is so often silent, it is frequently first noticed during a broader health check that includes blood tests and measurements of weight and waist. If you would like a structured review of your general health, you can look at what our Executive check-up covers and discuss with the team whether it suits your needs. Any abnormal liver results can then be followed up with a specialist.

Next steps

If you have abnormal liver tests or want to understand your risk of fatty liver disease, a specialist can review your results and explain what, if anything, needs to happen next.

• Learn more about our gastroenterology services.
• Be matched with a suitable specialist in a few steps: Find my physician.
• Explore the Executive check-up package.