The causes of acute pancreatitis are not well understood. There are several risk factors that are associated with acute pancreatitis. The actual cause that sets in the inflammation inside the pancreas are not clear.
Trypsin is an enzyme secreted by the pancreas. This enzyme helps to break down the proteins in food to help digest food. This is a very strong enzyme and while within the pancreas, it stays in an inactive form and has no digestive properties.
Once it moves out of the pancreas and into the intestines, it becomes active and starts to break down proteins.
In pancreatitis this trypsin may become active while still within the pancreas leading to damage to the pancreas and inflammation.
Presence of gall bladder stones
This is one of the commonest risk factors associated with acute pancreatitis. Gall bladder stones are hard stones that can form if the bile within the gall bladder has too much cholesterol and other minerals. Presence of gall bladder stones is called cholelithiasis.
These gall stones can also block the openings (ducts) to the pancreas. The blockage of the pancreatic ducts may lead to premature the activation of trypsin inside the pancreas and lead to acute inflammation.
Excessive alcohol consumption
Alcohol is normally metabolized by the liver. There are studies that suggest that alcohol may affect the normal workings of the cells of the pancreas and this may lead to a premature activation of the enzyme trypsin that damages the pancreas cells to lead to inflammation.
Alcohol is a direct risk factor for acute pancreatitis. Binge drinking or drinking large amounts of alcohol at one sitting also raises the risk of acute pancreatitis significantly.
Damage to the pancreas
Damage to the pancreas and its ducts during a type of surgery known as endoscopic retrograde cholangiopancreatography (ERCP). ERCP is generally used for the removal of the gall bladder stones.
Some medications may cause acute pancreatitis as their side effect. These include diuretics (water pills) like thiazides, furosemide, anticancer drugs like azathioprine, mercaptopurine, L-Asparaginase hormonal drugs like oestrogens (oral contraceptives), heart drugs like procainamide, ACE inhibitors, losartan, and antibiotics like sulphonamides, erythromycin, tetracycline, pentamidine, metronidazole, nucleoside-analogue reverse transcriptase inhibitors, anti-seizure drugs valproic acid, pain relievers like paracetamol, salicylates and general anesthetics like propofol.
Some poisons may also cause pancreatitis. These include methyl alcohol, poisoning with organophosphates, scorpion venom etc.
Some infections like measles virus, coxsackie B virus, ascariasis, mycoplasma, viral hepatitis (Hepatitis A, B and C), HIV, varicella virus, cytomegalovirus, Epstein-Barr virus, adenovirus, echo virus, leptospirosis, legionella, campylobacter jejuni, tuberculosis, mycobacterium avium and mumps virus may lead to pancreatic inflammation.
Obesity with a body mass index (BMI) of over 30 is a risk factor for pancreatitis.
Smokers and those over the age of 70 are at a greater risk of pancreatic inflammation.
Studies have shown that those with a specific genetic mutation, known as the MCP-1 mutation, are eight times more likely to develop severe acute pancreatitis than others with no such mutation.
Those with high blood levels of a special type of cholesterol called triglycerides especially while pregnant are at a greater risk of pancreatitis.
Other metabolic conditions that raise risk of pancreatitis include:-
- high blood calcium
- high levels of chylomicrons (special fat particles in blood)
- diabetic ketoacidosis
- high levels of ureas in blood
- low body temperature (hypothermia)
- advanced stages of pregnancy etc.
Lack of blood to the pancreas
Conditions leading to deprivation of blood to the pancreas may also lead to pancreatitis. These include systemic lupus erythematosus, polyarteritis nodosa, thrombotic thrombocytopaenic purpura, cardiopulmonary bypass, duodenal ulcer etc.
There may be no reason or cause or presence of a risk factor in some patients presenting with acute pancreatitis. These cases are termed idiopathic.