This article was last reviewed on
This article waslast modified on 5 November 2020.
Overview of the Liver

The liver is a vital organ located in the upper right-hand side of the abdomen. It performs numerous functions for the body: converting nutrients derived from food into essential blood components, storing vitamins and minerals, regulating blood clotting, producing proteins and enzymes, maintaining hormone balances, and metabolising and detoxifying substances that would otherwise be harmful to the body. The liver also makes factors that help the human immune system fight infection, removes bacteria from the blood, and makes bile, which is essential for digestion.

Bile, a greenish-yellow fluid consisting of bile acids (or salts) and waste products, such as bile pigments, flows through small bile ducts inside the liver. The bile flows from these small ducts into larger ones, like streams into a river, eventually leading to the common bile duct. The cystic duct connects the common bile duct to the gallbladder. After eating, the gallbladder, an organ that sits next to the liver and stores bile, releases bile into the small intestine where it helps to digest fats.

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About Liver Disease
  • Liver Conditions

    What is liver disease?

    Liver disease can result from acute or chronic damage to the liver, usually caused by infection, injury, exposure to drugs or toxic compounds, an autoimmune process, or an inherited defect. The disease can be classified by the effect it has on the liver and its functions.  The following table summarises the main categories of liver disease

    Liver Disease Examples of Causes Description
    An inflammation of the liver causing liver cell damage


    In the UK the most common causes are hepatitis A, B & C viruses
    Infection by one of the hepatitis viruses causing inflammation and damage to liver cells.  The damage may be cause quickly (acute hepatitis) or slowly (chronic hepatitis) which depends on the virus.
      Drugs or Chemicals
    Acute or chronic exposure to alcohol or paracetamol
    Many substances are processed and eliminated by the liver that may come from normal metabolism or ingested compounds such as drugs or alcohol. Some of these substances are potentially toxic.
    Alpha 1 antitrypsin deficiency, Haemochromatosis, Wilson’s disease.
    Some gene mutations result in diseases that may cause problems with depositions that result in damage to the liver.
    Type 1 diabetes, Sjorgren’s syndrome
    In these conditions, antibodies are produced which are directed against the liver causing damage.
      Non-alcoholic fatty liver - Metabolic syndrome Increased deposits of fat in the liver can lead to decreased amounts of healthy liver tissue.
    Prolonged damage to the liver replaced by scar tissue affecting liver structure & function
    Alcohol, hepatitis, biliary obstruction, congestive heart failure, inherited cause, drugs and sometimes unknown. Prolonged and persistent damage to the liver can lead to the accumulation of excess connective tissue in the organ. This is called fibrosis of the liver. Over a period of time fibrosis can progress to liver cirrhosis. In cirrhosis the structure of the liver changes with nodules of liver cells surrounded by fibrous tissue that does not function like healthy liver tissue.
    Can be either within the liver or outside the liver in the main bile duct
    Gallstones, tumours, trauma, inflammation or infection. Tumours, trauma, inflammation or gallstones of a sufficient size can cause blockage or obstructions in the ducts draining the liver (bile ducts). Bile and bilirubin then accumulate in the blood and the patient becomes jaundiced. Tumours or blood clots may also obstruct the vein from the liver. This may be chronic with few symptoms or acute and life threatening.
    Fatty Liver
    Fat is deposited in the liver which can reduce the amount of healthy liver tissue
    Alcohol, obesity, diabetes Fatty liver causes liver enlargement, tenderness and abnormal liver function. The most common cause is excessive intake of alcohol. Another cause is NASH (non-alcoholic steatohepatitis) which may progress to cirrhosis. It is seen most commonly in overweight and diabetic individuals.
    Tumours can damage healthy liver tissue and affect liver function
    Primary liver cancer or secondaries from another primary cancer spreading to the liver Hepatitis and cirrhosis may lead to liver cancer in some cases but cancer from other parts of the body that spreads to the liver (secondaries) is more common. People who have chronic hepatitis or cirrhosis may be checked on a regular basis for cancer, often with an alpha-fetoprotein (AFP) test and/or an ultrasound scan.
    Genetic defects can prevent vital liver functions and by depositing damaging substances
    Haemochromatosis, Wilsons disease, cystic fibrosis, alpha 1 antitrypsin deficiency Haemochromatosis is a genetic disorder resulting in excess iron storage in the liver, usually diagnosed in adults. Genetic diseases affecting children may involve a structural defect (biliary atresia), a missing enzyme or protein leading to damaging deposits such as galactose build-up in galactosaemia and copper accumulation in Wilson’s disease.


  • Signs and Symptoms

    Liver disease is often discovered during routine testing. It may not cause any symptoms at first or the symptoms may be vague, like weakness and loss of energy. In acute liver disease, most commonly symptoms related to:

    • problems handling bilirubin, including jaundice (yellowing of the skin and eyes), dark urine, and light stools
    • loss of appetite
    • nausea
    • vomiting
    • diarrhoea

    Chronic liver disease symptoms may not be present until the disease has reached an advanced stage. They include:-

    • jaundice, dark urine
    • abdominal swelling due to the accumulation of fluid (ascites)
    • pruritus (itching)
    • unexplained weight loss or gain
    • abdominal pain


  • Tests

    Three types of tests are often used to detect liver disease; these tests either measure the levels of specific enzymes, bilirubin, or protein present in the test sample (usually a blood sample).  Among the more common tests in these three categories are:

    1. Enzymes: Enzymes are proteins that help cells do their work. When cells are injured, enzymes can leak into the blood at higher-than-normal levels. Three common enzymes used to detect liver disease are:

    2. Bilirubin: Bilirubin, a waste product made from old blood cells, is a yellow compound that causes jaundice and dark urine when present in increased amounts. Two different tests of bilirubin are often used together, especially if a person has jaundice:

    • Total bilirubin - measures all the bilirubin in the blood
    • Conjugated bilirubin - measures a form made in the liver

    3. Protein: One of the main functions of the liver is to make protein. Two important liver tests include:

    • Albumin - measures the main protein made by the liver and tells how well the liver is making this protein
    • Total Protein - measures albumin and all other proteins in blood, including antibodies made to help fight off infections (antibodies are not made in the liver) 

    Doctors often use these tests together to tell whether liver damage has occurred and how severe it is. When requested together, these tests are called liver function tests.

    More specialised blood tests for liver disease may be requested by the doctor in addition to the tests above to investigate or monitor specific liver conditions. These tests are referred to within the individual sections on liver disorders on this site.