Pancreatitis

Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes (especially trypsin) that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years. It has multiple causes and symptoms.

Symptoms
The most common symptoms of pancreatitis are severe upper abdominal pain radiating to the back, nausea, and vomiting that is worsened with eating. The physical exam will vary depending on severity and presence of internal bleeding. Blood pressure may be elevated by pain or decreased by dehydration or bleeding. Heart and respiratory rates are often elevated. The abdomen is usually tender but to a lesser degree than the pain itself. As is common in abdominal disease, bowel sounds may be reduced from reflex bowel paralysis. Fever or jaundice may be present. Chronic pancreatitis can lead to diabetes or pancreatic cancer. Unexplained weight loss may occur from a lack of pancreatic enzymes hindering digestion.

Causes
Eighty percent of pancreatitis is caused by alcohol and gallstones. Gallstones are the single most common etiology of acute pancreatitis. Alcohol is the single most common etiology of chronic pancreatitis.

Some medications are associated, commonly including the AIDS drugs didanosine and pentamidine, diuretics, the anticonvulsant valproic acid, the chemotherapeutic agents L-asparaginase andazathioprine, estrogen by way of increased blood triglycerides, and cholesterol-lowering statins.

There is an inherited form that results in the activation of trypsinogen within the pancreas, leading to autodigestion. Involved genes may include Trypsin 1, which codes for trypsinogen, SPINK1, which codes for a trypsin inhibitor, or cystic fibrosis transmembrane conductance regulator.

Other common causes include trauma, steroid use, mumps, autoimmune disease, scorpion stings, high blood calcium, high blood triglycerides, hypothermia, and endoscopic retrograde cholangiopancreatography (ERCP). Pancreas divisum is a common congenital malformation of the pancreas that may underlie some recurrent cases. Pregnancy can be a cause, possibly by increasing blood triglycerides. Diabetes mellitus type 2 is associated with a 2.8-fold higher risk.

Less common causes include pancreatic cancer, pancreatic duct stones, vasculitis (inflammation of the small blood vessels in the pancreas), coxsackievirus infection, and porphyria—particularly acute intermittent porphyria and erythropoietic protoporphyria.

Diagnosis
Diagnosing pancreatitis requires two of the following: Amylase or lipase is frequently part of the diagnosis; lipase is generally considered a better indicator,     but this is disputed. Cholecystitis, perforated peptic ulcer, bowel infarction, and diabetic ketoacidosis can mimic pancreatitis by causing similar abdominal pain and elevated enzymes. The diagnosis can be confirmed by ultrasound and/or CT.
 * Characteristic abdominal pain
 * Blood amylase or lipase at least three times normal
 * Characteristic CT scan

Treatment
The treatment of pancreatitis is supportive and depends on severity. Morphine is preferred for pain relief. Oral intake, especially fats, are restricted. Fluids and electrolytes are replaced intravenously. When possible, the underlying cause is treated, such as by ERCP for gallstones or antibiotics for a bacterial infection. The patient is monitored for complications.

Prognosis
Several scoring systems are used to predict the severity of an attack of pancreatitis. They each combine demographic and laboratory data to estimate severity or probability of death. Examples include APACHE II, Ranson, and Glasgow. Apache II is available on admission; Glasgow and Ranson are simpler but cannot be determined for 48 hours. One form of the Glasgow criteria suggests that a case be considered severe if at least three of the following are true:
 * Age > 55 years
 * Blood levels:
 * Oxygen < 60mmHg or 7.9kPa
 * White blood cells > 15
 * Calcium < 2 mmol/L
 * Urea > 16 mmol/L
 * Lactate dehydrogenase (LDH) > 600iu/L
 * Aspartate transaminase (AST) > 200iu/L
 * Albumin < 32g/L
 * Glucose > 10 mmol/L

Complications
Early complications include shock, infection, systemic inflammatory response syndrome, low blood calcium, high blood glucose, and dehydration. Blood loss, dehydration, and fluid leaking into the abdominal cavity can lead to kidney failure. Respiratory complications are often severe. Pleural effusion is usually present. Shallow breathing from pain can lead to lung collapse. Pancreatic enzymes may attack the lungs, causing inflammation.

Late complications include recurrent pancreatitis and the development of pancreatic pseudocysts—collections of pancreatic secretions that have been walled off by scar tissue. These may cause pain, become infected, rupture and bleed, block the bile duct and cause jaundice, or migrate around the abdomen. Acute necrotizing pancreatitis can lead to a pancreatic abscess, a collection of pus caused by necrosis, liquefaction, and infection. This happens in approximately 3% of cases, or almost 60% of cases involving more than two pseudocysts and gas in the pancreas.