Primary biliary cirrhosis
What is primary biliary cirrhosis (PBC)?
PBC is a chronic disease that can, little by little, destroy some of the tubes linking your liver to your gut. These tubes are called bile ducts.
The bile ducts carry a fluid called bile to your gut (also known as your intestine or bowels).
When PBC damages your bile ducts, bile can no longer flow through them. Instead it builds up in the liver, damaging the liver cells and causing inflammation and scarring.
Over the years this damage becomes widespread. The liver becomes less able to repair itself, leading to a condition known as cirrhosis. The damage caused to your liver cells by cirrhosis can result in the failure of your liver carry out all of its jobs properly.
Bile is a yellow-green fluid produced by your liver which contains chemicals as well as waste products to aid digestion. It plays a central role in helping the body digest fat. It acts as a detergent, breaking the fat into very small droplets so that it can be absorbed from food in your gut. It also makes it possible for your body to take up the fat-soluble vitamins A, D, E and K from the food passing through the gut.
Why is it called PBC?
It is called primary biliary cirrhosis because the disease attacks the bile (biliary) ducts inside the liver. This leads to scarring (fibrosis) and then to cirrhosis. In this case ‘primary’ does not mean first but that there is no known reason for this damage to happen.
The name PBC is a little misleading. Many people do not have cirrhosis when they are first diagnosed or for many years afterwards. Indeed, many people with PBC never go on to get cirrhosis.
Because it blocks or stops the flow of bile, PBC is known as a ‘cholestatic’ liver disease.
Who is at risk of PBC?
Nine out of ten people who get PBC are women. No one knows why this is. In particular the following women are most at risk:
- women who are middle aged or older
- women who have a family history of PBC.
There is no evidence that PBC can be passed on to others by simple contact, kissing, blood or sexual contact.
What are the causes of PBC?
Over-consumption of alcohol and hepatitis are the main causes of cirrhosis in the UK, accounting for more than half of all cases. Despite the strong association between alcohol and liver disease, drinking alcohol does not cause PBC.
PBC is believed to be an autoimmune disease. This is a disease where the body attacks itself. In this case, your body’s defence against germs and infections – the immune system – mistakes the cells lining the bile ducts as ‘foreign’ and attacks them.
Why this happens is still not known. Some medical specialists believe that something may trigger your body into making this mistake. Possible causes of this ‘trigger’ could be:
- an infection
- some form of toxin (poison) taken in from the environment.
Occasionally PBC comes to light during or just after pregnancy. It is not clear whether pregnancy may spark it off or, because pregnant women are under close medical supervision, the symptoms of PBC are first noticed during pregnancy.
This external trigger probably starts PBC only in people who are already at risk because they have inherited certain genes from their parents.