For an explanation of the pancreas, please see the description under "What is the pancreas?" in Pancreatic Diseases.
What is pancreatitis?
Pancreatitis is an acute or chronic inflammation of the pancreas. Acute attacks are often characterized by severe abdominal pain that radiates from the upper belly through to the back and can cause effects ranging from mild pancreatic swelling to life-threatening failure of many organs. Chronic pancreatitis is a progressive condition that results in permanent damage of pancreatic tissue. Recurrent acute attacks can lead to chronic pancreatitis.
The pancreas is a narrow, flat organ located deep in the abdominal cavity, behind the stomach and below the liver. It has head, middle, and tail sections. Its head section connects to the duodenum, the first part of the small intestine. Inside the pancreas, small ducts (tubes) feed digestive enzymes produced by the pancreas into the pancreatic duct. This large duct carries the digestive enzymes down the length of the pancreas, from the tail to the head section, and into the duodenum. The common bile duct also runs through the head section of the pancreas, carrying bile from the liver and gallbladder into the small intestine. The bile duct and pancreatic duct usually join just before entering the duodenum and share a common opening into the small intestine.
The pancreas has two kinds of tissues: exocrine and endocrine. Exocrine tissues make powerful enzymes that help digest fats, proteins, and carbohydrates in the small intestine as well as make bicarbonate that helps neutralize stomach acids. Endocrine tissues have "islets" or clusters of certain cell types that produce the hormones insulin and glucagon (among other hormones), whihch are vital for the transportation of glucose into the body's cells and for maintaining normal blood levels of glucose (blood sugar).
The cells of the exocrine pancreas make, store, and release digestive enzymes. Many of these digestive enzymes are inactive within the cell but activated when they reach the small intestine. Obstruction of the common bile and pancreatic ducts, most commonly by gallstones, causes an accumulation and early activation of digestive enzymes, leading to pancreatic damage and pancreatitis.
Pancreatitis can also occur without the presence of an obstruction. In addition to the normal stress on pancreatic cells and genetic differences between individuals, external stressors such as alcoholism affect regular pancreatic cell function. The stress may not be sufficient to cause pancreatitis in all individuals, but in certain people, it appears to substantially increase the risk by adversely affecting normal digestive enzyme synthesis and release or by causing early activation of these enzymes. The resulting cell damage leads to cell death and, if the damaging events and inflammatory response are too great or persistent, pancreatitis may develop.
Pancreatitis occurs more frequently in men than in women and is known to be linked to and aggravated by alcoholism and gallbladder disease. In the latter case, this happens because of obstruction of the common duct from the gallbladder and pancreas into the intestine. Obstruction is most frequently due to gallstones and sometimes to biliary sludge. Alcoholism and gallbladder disease are responsible for about 80% of acute pancreatitis attacks and figure prominently in chronic pancreatitis. Another 10% of the time the cause is idiopathic, and the other 10% of the time it is due to one of the following:
- Drugs such as valproic acid and estrogen
- Viral infections such as mumps, Epstein-Barr, and hepatitis A, B and E
- Exceedingly high blood triglyceride level, hyperparathyroidism, or high blood calcium level
- Cystic fibrosis and inherited defects that result in early activation of digestive enzymes
- Pancreatic cancer
- Surgery in the area of the pancreas (such as bile duct surgery)
- Trauma to the abdomen ("blunt trauma")