Pancreatitis is inflammation of the pancreas, an organ located behind the stomach. It can be either acute or chronic.

Acute pancreatitis is characterized by rapid inflammation of the pancreas, often caused by factors like gallstone blockage or excessive alcohol consumption. Chronic pancreatitis, on the other hand, is a slow, progressive inflammation that may result from long-term alcohol abuse, obstructions in the pancreatic duct, or genetic factors.

The causes of acute pancreatitis include:

1. Gallstones: A blockage in the bile duct caused by gallstones prevents the flow of digestive enzymes from the pancreas to the small intestine.
2. Alcohol consumption: Excessive and prolonged alcohol consumption can lead to pancreatic inflammation, resulting in acute pancreatitis.
3. Certain medications: Drugs such as steroids, antibiotics, and diuretics can also cause pancreatitis in some individuals.
4. Trauma: Injury to the pancreas, like abdominal trauma or surgery, can trigger inflammation.
5. Infections: Certain viral or bacterial infections can contribute to pancreatitis.
6. High triglyceride and calcium levels: Elevated levels of these substances in the blood can also trigger the condition.

Pathogenesis begins when one or more etiological factors damage the pancreas, producing digestive enzymes such as trypsin, phospholipase, and elastase. Usually, these enzymes activate in the small intestine to aid food digestion. However, in pancreatitis, they activate prematurely within the pancreas itself, initiating a process known as autodigestion. It leads to inflammation and damage to pancreatic cells, blood vessels, and surrounding tissues.

As a result, inflammatory mediators, including cytokines, chemokines, and proteins, are released. This release triggers fluid accumulation, known as edema, and in severe cases, the death of pancreatic tissue or necrosis.

Acute pancreatitis is classified as mild (edematous or interstitial) or severe (necrotizing). In severe cases, patients may experience a permanent decrease in pancreatic endocrine and exocrine function, leaving them highly susceptible to complications such as pancreatic necrosis, organ failure, and septic complications.