Liver Abnormal Liver Blood Tests

What are the liver blood tests?

Liver blood tests, commonly known as liver function tests or LFTs, are a collection of biochemical tests performed on a blood sample. They are often checked routinely as part of a set of blood tests including:

  • where a liver problem is suspected
  • investigation of a new medical problem
  • a review of medications
  • for a health check
  • for a diabetes review

Abnormal Liver Blood Tests

The LFTs are a panel of tests each providing slightly different information. These include:

  • Bilirubin - the yellow pigment formed from the breakdown by the body of red blood cells. When high, the patient can notice yellowing of the eyes or skin - jaundice
    • can be elevated in a wide range of liver and blood conditions
    • has 2 forms, conjugated (direct) and unconjugated (indirect) - isolated mild elevation in bilirubin, if predominantly unconjugated, can be considered a normal variant with no adverse health consequences, known as Gilbert’s syndrome
  • ALT (alanine aminotransferase) - this is an important enzyme in everyone’s liver, but when liver cells are damaged, higher levels are detected in the blood
    • High levels imply “hepatitis” which means inflammation of the liver cells
    • Normal levels do not exclude advanced liver disease
  • AST (aspartate aminotransferase) - similar to ALT, but levels are relatively higher compared with ALT in the setting of advanced liver fibrosis/cirrhosis and in alcoholic hepatitis. Not routinely included in the LFT panel
  • ALP (alkaline phosphatase) - this protein can be elevated in many liver diseases, but is particularly associated with conditions causing blockage to the bile ducts
    • Forms of this enzyme (isoenzymes) are produced by bone, intestine and placenta, so other sources of high levels should be considered
  • • γGT, gammaGT (gamma glutamyl transferase) is another enzyme found in the liver which can be detected in the blood at higher levels when there is liver damage. γGT can be elevated for a myriad of reasons, but is frequently elevated in fatty liver, whether alcohol-related or non-alcoholic. The γGΤ level does not correlate with the severity of liver disease and because it is a non-specific test, it is not usually a routine part of the LFT panel

What is the significance of abnormal liver tests?

This gets quite complicated and there is no short answer, but the majority of liver test abnormalities to not reflect a severe underlying problem. Your doctor will look at the test results including:

  • The absolute levels (are they very high?)
  • The relative levels (which of the liver tests is most abnormal?) - this can give clues as to whether this is a problem with the liver cells or the bile ducts, for example
  • The timecourse - is it acute (occurring over a short time period) or chronic (a longer term, grumbling problem)?

What are the common causes of abnormal liver tests?

Mildly abnormal liver tests may be caused by:

  • Non-alcoholic fatty liver disease (NAFLD)
  • High alcohol intake and alcohol related liver disease
  • Side effect of medications or supplements
  • Blockages to the bile ducts
  • Viral infections (sometimes mild and reversible, sometimes chronic hepatitis viruses that can cause
    significant liver damage)
  • Autoimmune and biliary conditions including:
    • Autoimmune hepatitis
    • Primary biliary cholangitis
    • Primary sclerosing cholangitis
  • Metabolic liver diseases other than NAFLD, including:
    • Haemochromatosis (iron overload)
    • Wilson’s disease (copper overload)
    • Alpha-1-antitrypsin deficiency (abnormal protein deposition)
  • Effects of conditions affecting other parts of the body including:
    • Heart problems (congestive cardiac failure)
    • Coeliac disease
    • Arthritis and connective tissue disorders
  • Tumours or lesions in the liver
    • Benign or malignant
    • Primary liver tumours (hepatocellular carcinoma and cholangiocarcinoma)
    • Secondary liver tumours (metastases from other primary sites, e.g. the colon)

How will these abnormalities be investigated?

Further investigations will depend on the picture of liver tests abnormalities but may include the following:

  • A detailed medical history including risk factors for liver diseases, other medical problems, any medications or supplements, use of alcohol and other lifestyle matters
  • Further blood tests (“liver screen”) including tests for hepatitis viruses, autoimmune conditions and metabolic liver conditions
  • Imaging, usually starting with an ultrasound scan, to look for structural abnormalities including:
    • Bile duct problems or blockages, for example gallstones
    • Signs of cirrhosis or advanced liver scarring
    • Signs of fatty liver
    • Lumps, cysts or tumours
  • Non-invasive tests of disease severity, including FibroScan® or specialist blood markers