In many cases, a suspected diagnosis of primary biliary cirrhosis (PBC) is made when carrying out a blood test for another, unrelated condition.
Blood tests
Damage to the bile ducts and liver leads to an increase in enzymes (proteins) that are produced by your liver. The high level of enzymes can be detected by having a blood test.
A diagnosis of PBC can usually be confirmed by checking your blood for a substance called anti-mitochondrial antibodies (AMAs). In PBC, AMAs are produced by the immune system (the body’s natural defence against infection and illness). They are present in 95% of people with PBC.
You may also have a high level of bilirubin in your blood. Bilirubin is a yellow substance that is produced when red blood cells are broken down. The liver usually ‘picks up’ bilirubin and it is passed out of your body in urine. If there is something wrong with your liver or bile ducts, too much bilirubin will be produced, and this will show up on a blood test.
Liver biopsy
You may also be referred for a liver biopsy. This involves a small sample of liver tissue being taken so that it can be studied under a microscope.
Most liver biopsies can be carried out under local anaesthetic (painkilling medication). The sample is obtained using a long needle. The sample will be examined for evidence of missing or inflamed (swollen) bile ducts.
A liver biopsy is not usually necessary to diagnose PBC, which is usually confirmed by the presence of AMAs. However, it can be used to assess the extent of the damage to your liver.
See the Health A-Z topic about Biopsies for more information about the procedure.
