Trypsin
Acute pancreatitis is caused when something goes wrong with a chemical called trypsin. Trypsin is an enzyme that is produced by the pancreas. It is used to help break down the proteins in food to aid digestion.
When trypsin is produced by the pancreas, it remains in an ‘inactive’ state and has no digestive properties. It is not until it is moved out of the pancreas and into the intestines that it becomes active and is able to start breaking down proteins.
In cases of acute pancreatitis, trypsin is activated while it is still in the pancreas. The trypsin begins to break down the cells of the pancreas. In other words, the pancreas starts to digest itself, causing it to become irritated and inflamed.
Risk factors
Alcohol misuse and gallstones are the two main risk factors for acute pancreatitis.
Alcohol misuse
It is not completely understood how alcohol activates trypsin when it is still the pancreas.
One theory is that the ethanol molecules in alcohol interfere with the normal workings of the cells of the pancreas, causing them to activate trypsin prematurely.
Whatever the cause, there is a clear link between alcohol misuse and acute pancreatitis. Acute pancreatitis is known to occur in 10% of cases of chronic alcohol misuse.
Chronic alcohol misuse is defined as drinking more than 10 units of alcohol a day. More than four pints of lager or more than five glasses of wine a day on a daily basis equals more than 10 units of alcohol a day.
See Useful links for more information about alcohol misuse and advice about alcohol consumption.
Gallstones
Gallstones are hard pieces of stone-like material that can form if your bile has too much cholesterol in it.
Sometimes, a gallstone can move out of the gallbladder and block the openings (ducts) to the pancreas. The blockage interferes with the normal workings of the pancreas, activating trypsin while it is still inside the pancreas and causing the pancreas to become irritated and inflamed.
For more information see the A-Z topic on gallstones.
Less common causes
Less common causes of pancreatitis include:
- bacterial infections, such as salmonella (a type of food poisoning), or Legionnaires’ disease (an infection that is usually caused by inhaling droplets of contaminated water),
- viral infections, such as mumps or hepatitis B,
- conditions where the immune system attacks healthy tissue (autoimmune conditions), such as lupus or Sjogren’s syndrome, and
- injury to the pancreas.
Idiopathic pancreatitis
In an estimated 15% of cases of acute pancreatitis, no obvious cause can be found. This type of pancreatitis is known as idiopathic pancreatitis.
