Guide to liver health and liver function tests

What are the signs of liver damage, and how can you check your liver function from home?

Your liver has over 500 functions, from filtering out toxins to regulating chemicals (like hormones) and storing nutrients and glucose for energy. It’s capable of repairing itself if damage is caught early enough and acted on. In fact, nine in ten cases of liver damage are preventable [1]. 

If you are worried about your liver health or are looking at whether you could benefit from a Liver Function Blood Test, this guide aims to give you further context and information about your liver function. 

In this blog, we cover:  

How the liver works

Think of your liver as the ultimate detox centre, like a high-end spa for your body. A healthy liver filters out toxins from your blood, helps with digestion, stores energy, and even produces proteins your body needs. It's a vital organ (your body’s largest solid, internal organ) and holds about 13% of your total blood supply.   

Your liver comprises two main lobes and two smaller lobes - the caudate and quadrate. Inside these lobes are liver cells called hepatocytes, which secrete bile. Bile is a yellow-green fluid that helps break down fat in your body. It's stored in your gallbladder and released when your body needs it. 

The main functions of your liver are to: 

  • regulate blood sugar 
  • remove toxins 
  • store essential vitamins 
  • control hormone production 

Out of all the functions it performs, removing toxins from the blood is one of its most important.  

When your body is exposed to harmful substances (such as drugs and alcohol), toxins can enter. Similarly, digesting food also produces toxins such as ammonia, which is released when your body breaks down proteins. Your liver uses enzymes and oxygen to break down these toxins and combines them with either sulphur or amino acids to remove them from the blood through bile or urine.  

Where is the liver located?  

Your liver is in your abdomen, under your ribcage on the right side. Some people may feel a dull or throbbing pain in their abdomen due to liver damage, though that isn’t always the case. It isn’t uncommon for people with liver problems to describe pain in their back or shoulders, known as referred pain.    

Common symptoms of liver disease

If identified early enough, healthy lifestyle changes can help to reverse or prevent liver damage. However, in many cases, people with liver disease don’t have any noticeable symptoms until their liver is badly damaged.  

Early symptoms of liver disease include: 

  • abdominal pains 
  • weight loss 
  • tiredness 
  • loss of appetite 
  • feeling sick 

Later symptoms of liver disease include: 

  • vomiting blood or blood in the stool 
  • swelling of the abdomen, legs, and ankles 
  • confusion or drowsiness 
  • diarrhoea 
  • itchy skin 
  • yellowing of the eyes and skin (jaundice) 
  • pale stools or very dark/tarry stools 
  • easy bruising, nose bleeds, bleeding gums and difficulty stopping bleeds 
  • tremors 
  • enlarged breasts and shrunken testes in men 
  • irregular periods in women 

Remember, these symptoms can vary in severity, and not everyone with liver disease will experience all of them.  

We explain how to take care of your liver in our blog: 7 ways to keep your liver healthy.  

What can cause liver damage?

Common causes of liver disease are regularly drinking too much alcohol, taking certain drugs (including prescribed and over-the-counter medications), being overweight, and infections such as viral hepatitis. Less common causes include cancer and genetic and autoimmune conditions.  

Five common causes of liver damage: 

  1. Drinking too much – long-term heavy drinking and prolonged alcohol misuse can lead to alcohol-related liver disease (ARLD). 
  2. Obesity – poor diet or risk factors like obesity, high cholesterol, and type 2 diabetes can lead to non-alcohol-related liver disease (NARLD).  
  3. Parasites and viruses – a viral infection can be a cause of hepatitis (inflammation of the liver).  
  4. Immune system abnormalities – some autoimmune diseases can cause the immune system to attack the liver cells. 
  5. Genetic disorders like haemochromatosis (iron overload) – some genetic factors may cause cirrhosis (liver scarring). 

What is haemochromatosis (iron overload disorder)? 

Haemochromatosis is an inherited disorder that causes a steady build-up of iron in the body. The liver is sensitive to the effects of excess iron, and it can cause cirrhosis, which increases the risk of liver cancer.  

As well as affecting the liver, excess iron can also be stored in the heart and pancreas, and prolonged high iron levels can cause heart problems and diabetes. 

Symptoms of haemochromatosis include: 

  • fatigue 
  • joint pain 
  • erectile dysfunction in men 
  • irregular/absent periods in women 
  • weight loss 

There is currently no cure for haemochromatosis, but treatment can help reduce iron levels in the body and reduce the risk of damage. If your doctor suspects haemochromatosis, they may advise a blood test to check your iron status.  


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Types of liver disease

There are over 100 different types of liver disease, which affect over 2 million people in the UK. We’ll talk you through the main types of liver disease.  


Hepatitis is the inflammation of the liver and is usually the result of a viral infection or excess toxins [1]. Heavy alcohol use, some medications, and certain medical conditions can cause hepatitis.  

There are several types of hepatitis, but the three most common viral types are:  

  • Hepatitis A  
  • Hepatitis B  
  • Hepatitis C  

Hepatitis can be acute (where the infection lasts six months or less) or chronic (where inflammation lasts longer than six months). 

Primary biliary cholangitis 

Primary biliary cholangitis (PBC) - previously known as primary biliary cirrhosis - is an autoimmune disease where the immune system attacks the liver cells, mistaking them for foreign objects in the body like bacteria or viruses. This immune response leads to bile duct swelling, which restricts bile in the liver. Without treatment, the inflammation and fibrosis (that PBC causes) can progress and lead to scarring and liver failure. 

Although PBC can affect both sexes, women are more likely than men to develop the autoimmune condition. 

Alcohol-related liver disease (ARLD) 

Alcohol-related liver disease (ARLD) happens after years of drinking too much alcohol. ARLD is part of a progression - often starting with fatty liver disease and advancing to alcoholic hepatitis. If drinking continues, alcoholic cirrhosis may occur and cause scar tissue to form in the liver. 

The treatment for ARLD is to stop drinking. This may be easier said than done, especially if you depend on alcohol. However, there are alcohol support services available. If you have stopped drinking and still develop complications of cirrhosis, then you may be considered for a liver transplant.  

Non-alcoholic fatty liver disease (NAFLD) 

Non-alcoholic fatty liver disease (NAFLD) describes a range of conditions caused by a fatty liver, which can happen without prolonged exposure to alcohol.  

The four stages of NAFLD are: 

1. Simple fatty liver (steatosis)  

Simple steatosis is the mildest form of NAFLD and means there are high-fat levels in the liver. This stage of NAFLD is often suspected when a liver function blood test shows elevated liver enzymes and other diseases associated with a fatty liver have been excluded. This stage of NAFLD can be reversed easily by following appropriate lifestyle changes. Simple steatosis does not cause serious liver damage, but if the build-up of fat increases, it can lead to non-alcoholic steatohepatitis (NASH). 

2. Non-alcoholic steatohepatitis (NASH)  

NASH is when excessive fat in the liver causes inflammation and injury to the liver cells, which leads to scar tissue (fibrosis) forming. The build-up of fat seen in people with NASH is similar to fatty liver seen in people with the alcohol-related form of liver disease, but NASH occurs in people who don't abuse alcohol. 

3. Fibrosis  

Fibrosis is when persistent inflammation in the liver causes scar tissue around the liver and nearby blood vessels. It can take years for fibrosis to develop, and making healthy lifestyle changes can prevent it from progressing. 

4. Cirrhosis  

NASH-related cirrhosis (NRC) is the most serious form of NAFLD, caused by scarring throughout the liver. Without intervention, cirrhosis can eventually progress to liver failure, which is a life-threatening condition. Liver failure can cause serious complications, including increasing pressure in the brain and excessive bleeding in the body. People who have NRC may require a liver transplant. 

The main treatment for NAFLD is to adopt a healthy lifestyle, including losing weight, eating a healthy diet, exercising regularly, and stopping smoking. While NAFLD is not caused by alcohol, you may be advised to cut down or stop drinking. If you have NAFLD, your doctor may also focus on treating an associated condition like diabetes or high cholesterol.  

Liver function tests

If you are concerned about liver disease, you can discuss any symptoms and your lifestyle habits (including diet and alcohol intake) with a doctor. If you visit a doctor, they may also perform a physical examination to check if the liver or spleen is enlarged.  

A Liver Function Blood Test will check the specific markers indicative of liver health, as they can be elevated if the liver is damaged, or the biliary system is obstructed. If you get an abnormal liver result, you may need to repeat your liver function test in line with your doctor's guidance. 

Your liver blood test results and lifestyle information will help a doctor assess your risk of NAFLD and AFLD. 

1. Liver Blood Test 

A blood test that looks at your liver enzymes, including bilirubin, alkaline phosphatase (ALP), alanine transferase (ALT), and gamma GT (GGT), can give you a good overview of your liver health.  

Early detection is so important for your liver, as liver damage is usually reversible in its early stages.  

2. Further tests 

If liver damage is suspected, your doctor may order imaging tests or a liver biopsy to take a closer look at how well your liver is working.  

What happens when liver enzymes are high?

Your doctor will assess your liver enzyme test results alongside your alcohol intake, diet, and overall health and lifestyle information.  

If your liver enzymes are high, your doctor may advise you to make lifestyle changes (losing weight and exercising or abstaining from alcohol), investigate associated conditions (high cholesterol, diabetes or an infection), or refer you for a scan to take a closer look at your liver (as liver enzymes can be affected by liver structure or bile duct abnormalities). 

The liver enzymes, including bilirubin, alkaline phosphatase (ALP), alanine transferase (ALT), and gamma GT (GGT), can be elevated if the liver is damaged or if the biliary system is obstructed. A liver biopsy may also be required to confirm a diagnosis of alcoholic hepatitis, but your doctor will decide if this is necessary. 

Related tests 

  • Liver Function Blood Test our liver function profile can be carried out at home as a simple finger-prick test. It includes enzymes such as GGT and ALT to see how well the liver is functioning. 
  • Advanced Well Man Blood Test or Advanced Well Woman Blood Test — our best-selling comprehensive health checks for men and women give a more detailed overview of your health.  
  • Ultimate Performance Blood Test our ultimate blood test for men and women gives you our most comprehensive health check, including advanced profiles for your hormone health and thyroid function, as well as liver health and iron status. 


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  1. British Liver Trust (2022) Liver disease in numbers – key facts and statistics, British Liver Trust. Available at: (Accessed: 20 September 2023).  

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