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Pancreatitis

Definition

Pancreatitis is an inflammation of the pancreas, an organ that is important in digestion. In pancreatitis, normal digestive enzymes act abnormally to break down the pancreas itself.

Description

The pancreas is a complex organ with many critical functions for normal digestion and regulation of blood sugar. When inflamed, as in pancreatitis, several potent enzymes are inappropriately activated within the organ itself. In acute pancreatitis, inflammation is sudden and causes symptoms. In almost 90% of acute cases, the symptoms disappear within one week after treatment, and the pancreas returns to its normal function. With chronic pancreatitis, damage to the pancreas occurs over longer periods of time. Symptoms may be persistent or sporadic, as the pancreas is slowly but permanently impaired. More than 90% of pancreatic tissue will be destroyed before serious symptoms begin. Late signs of chronic pancreatitis include diabetes mellitus and malabsorption syndromes in which nutrients are poorly absorbed from the digestive tract.

Causes and symptoms

There are a number of causes of acute pancreatitis, the most common of which are gallstones and alcoholism. These two diseases are responsible for more than 80% of all hospitalizations for acute pancreatitis. Gallstones may obstruct normal drainage from the pancreas into the small intestine, resulting in a backup of normal pancreatic secretions and inflammation of the pancreas until the obstruction is relieved.

The mechanism by which alcohol inflames the pancreas is not well understood. It is thought that alcohol causes proteins to collect in the pancreas and results in obstruction and calcification of the organ.

Other factors in the development of acute pancreatitis include:

• certain drugs, including estrogens, sulfonamides, and diuretics
• interferon and ribavirin therapy for chronic hepatitis C infection
• infections
• structural problems of the pancreatic duct and common bile duct
• injury to the abdomen
• abnormally high levels of circulating fats in the bloodstream
• high blood levels of calcium
• complications from kidney failure or transplant
• a hereditary tendency toward pancreatitis
• various forms of vasculitis (inflamed blood vessels)

In pancreatitis, enzymes become prematurely activated so that they actually begin their digestive functions within the pancreas. The pancreas, in essence, begins digesting itself. Digestion of the blood vessels in the pancreas results in bleeding. Other active pancreatic chemicals cause blood vessels to become leaky, and fluid begins seeping into the abdominal cavity. The activated enzymes also gain access to the bloodstream through leaky, eroded blood vessels, and begin circulating throughout the body.

Pain is a major symptom in acute pancreatitis, and it is usually quite intense and steady, located in the upper abdomen, and radiating to the patient's back. Nausea, vomiting, and abdominal swelling are also common symptoms. A patient will often have a slight fever, with an increased heart rate and low blood pressure.

Patients with acute pancreatitis are at risk of complications related to shock, a serious syndrome that occurs when the blood pressure is too low to get adequate circulation to critical organs. Without adequate blood pressure, organs are deprived of oxygen, nutrients, and waste removal and may not function well. Kidney, respiratory, and heart failure are serious possible outcomes of shock.

Even if shock does not occur, circulating pancreatic enzymes and related toxins can cause damage to the heart, lungs, kidneys, lining of the gastrointestinal tract, liver, eyes, bones, and skin. As the pancreatic enzymes affect blood vessels, the risk of blood clots increases. When blood flow is blocked by clotting, the supply of oxygen is further decreased to various organs and additional damage done.

Other serious complications of acute pancreatitis include pancreatic necrosis, abcess, and pseudocyst formation. Pancreatic necrosis occurs when a significant portion of the pancreas is permanently damaged during an acute attack. Pancreatic necrosis has an increased risk of death and an increased chance of pancreatic infection. A pancreatic abscess is a local collection of pus that may develop several weeks after the illness subsides. Another late complication of pancreatitis, occurring several weeks after the illness begins, is called a pancreatic pseudocyst, which occurs when dead pancreatic tissue, blood, white blood cells, enzymes, and fluid leaked from the circulatory system accumulate. Pseudocysts cause recurrent abdominal pain and also press on other nearby structures in the gastrointestinal tract, causing disruption of function. Pseudocysts are life threatening when they become infected (abscess) and rupture. Simple rupture of a pseudocyst causes death 14% of the time, but rupture complicated by bleeding causes death 60% of the time.

In severe cases of pancreatitis, called necrotizing pancreatitis, the pancreatic tissue begins to die, and bleeding increases. Due to the bleeding into the abdomen, two distinctive signs may be noted in patients with necrotizing pancreatitis. Turner's sign is a red-dish-purple or greenish-brown color to the area between the ribs and the hip (flank). Cullen's sign is a bluish color around the navel.

Alcohol abuse is the cause of tissue damage in 80% of cases of chronic pancreatitis. Tissue damage occurs more slowly, and many digestive functions become disturbed. The quantity of hormones and enzymes normally produced by the pancreas begins to decrease, resulting in the inability to appropriately digest food. Fat digestion, in particular, is impaired. A patient's stools become greasy as fats are passed out of the body. The inability to digest and use proteins results in smaller muscles (wasting) and weakness. The inability to digest and use the nutrients in food leads to malnutrition, vitamin deficiencies, and a generally weakened condition. As the disease progresses, permanent injury to the pancreas can lead to diabetes.

Diagnosis

Diagnosis of pancreatitis, whether acute or chronic, is not simple. History and physical exam are very important, as well as imaging studies and laboratory tests. Levels of amylase and lipase that are three times above the upper limit of normal are predictive of acute pancreatitis. Other abnormalities in the blood may also point to pancreatitis, including increased white blood cells, changes due to dehydration from fluid loss, and abnormalities in the blood concentration of calcium, magnesium, sodium, potassium, bicarbonate, and glucose.

X rays or ultrasound examination of the abdomen may reveal gallstones, possibly responsible for blocking the pancreatic duct. The gastrointestinal tract will show signs of inactivity (ileus) due to the presence of pancreatitis. Chest x rays may reveal abnormalities due to shallow breathing or due to lung complications from the circulating pancreatic enzyme irritants. Computed tomography (CT) scans of the abdomen may reveal the inflammation and fluid accumulation of pancreatitis.

In the case of chronic pancreatitis, lipase and amylase levels will no longer be elevated. However, blood tests will reveal the loss of pancreatic function that occurs over time. Blood sugar (glucose) levels will rise, eventually reaching the levels consistent with diabetes. The levels of various pancreatic enzymes will fall, as the organ is increasingly destroyed and replaced by non-functioning scar tissue. Calcification of the pancreas can also be seen on x rays. Endoscopic retrograde cholangiopancreatography (ERCP) may be used to diagnose chronic pancreatitis in unclear cases. In this procedure, the physician uses a medical instrument fitted with a fiber-optic camera to inspect the pancreas.

Recent developments in understanding of genetics and the role of genetics in susceptibility to pancreatitis may soon lead to use of genetic testing for early diagnosis and prognosis of pancreatitis. The testing can detect abnormalities in trypsin and trypsin inhibitor genes and cystic fibrosis genes.

Treatment

Treatment of acute pancreatitis involves replacing lost fluids intravenously (in a vein). These intravenous (IV) solutions need to contain appropriate amounts of salts, sugars, and sometimes even proteins, in order to correct the patient's disturbances in blood chemistry. Pain is treated with a variety of medications, chiefly meperidine. To decrease pancreatic function, the patient is not allowed to eat. A thin, flexible tube (nasogastric tube) may be inserted through the patient's nose and down into the stomach. The nasogastric tube can empty the stomach of fluid and air that may accumulate due to the inactivity of the gastrointestinal tract.

The patient will need careful monitoring to identify complications that may develop. Infections will require antibiotics through the IV. Severe necrotizing pancreatitis may require surgery to remove part of the dying pancreas, especially if infection has begun. A pancreatic abscess can be drained by a needle inserted through the abdomen and into the collection of pus (percutaneous needle aspiration). An abscess may also require surgical removal. In 25-40% of cases, pancreatic pseudocysts may shrink on their own or continue to expand, requiring needle aspiration or surgery. Surgery may be necessary for the removal of gallstones.

Because chronic pancreatitis often includes repeated flares of acute pancreatitis, the same kinds of basic treatment are necessary. Treatment of chronic pancreatitis caused by alcohol consumption requires that the patient stop drinking alcohol entirely. A low-protein and low-fat diet is prescribed. As chronic pancreatitis continues and insulin levels drop, a patient may require insulin injections to be able to process sugars in the diet. Pancreatic enzymes can be replaced with oral medications. As the pancreas is progressively destroyed, some patients stop feeling the abdominal pain that was initially so severe. Others continue to have constant abdominal pain, and may require a surgical procedure for relief.

Prognosis

When necrosis and bleeding are present, as many as 50% of patients with pancreatitis may die. Overall, the mortality rate for patients with mild acute pancreatitis is less than 1%. Those with sever pancreatitis have a mortality rate as high as 25%.

Ranson's criteria can help determine the severity of the disease. The first five categories are evaluated when the patient is admitted to the hospital, including:

• age over 55 years
• blood sugar level over 200 mg/dl
• serum lactic dehydrogenase over 350 IU/L
• AST over 250 μ (a measure of liver function, as well as a gauge of damage to the heart, muscle, brain, and kidney)
• white blood count over 16,000 μL

The following six of Ranson's criteria are reviewed 48 hours after the patient's admission to the hospital, including:

• greater than 10% decrease in hematocrit (a measure of red blood cell volume)
• increase in BUN (blood urea nitrogen, an indicator of kidney function) greater than 5 mg/dL
• blood calcium less than 8 mg/dL
• PaO₂ (a measure of oxygen in the blood) less than 60 mm Hg
• base deficit greater than 4 mEg/L (a measure of change in the normal acidity of the blood)
• fluid sequestration greater than 6 L, or 13 pt (an estimation of the quantity of fluid that has leaked out of the blood circulation and into other body spaces)

Once it is determined how many of Ranson's signs are present in the patient, the physician can better predict the risk of death. A patient with less than three positive Ranson's signs has less than a 5% chance of dying. A patient with three to four positive Ranson's signs has a 15-20% chance of death.

The results of a CT scan can also be used to predict the severity of pancreatitis. Slight swelling of the pancreas indicates mild illness. Significant swelling, especially with evidence of destruction of the pancreas and/or fluid build-up in the abdominal cavity, indicates more severe illness and a worse prognosis.

Health care team roles

The physician will make a full physical examination of the patient to determine which tests are necessary. Radiologic technologists will perform imaging studies and clinical laboratory technicians will perform the laboratory tests. Nurses have an active supportive role throughout the patient's illness.

Prevention

Alcoholism is essentially the only preventable cause of pancreatitis. Patients with chronic pancreatitis must stop drinking alcohol entirely. The drugs that may cause pancreatitis should also be avoided when possible.

Resources

BOOKS

Izenberg, Neil, ed. Human Disease and Conditions. Charles Scribner's Sons, 2000: 643-644.

Toskes, Phillip P., and Norton J. Greenberger. "Disorders of the Pancreas." In Harrison's Principles of Internal Medicine, edited by E. Braunwald, et al. McGraw-Hill, 2001: 1788-1803.

PERIODICALS

Bates, Betty. "Pancreatitis Difficult Etiology Becoming Easier to Pinpoint." Family Practice News (March 15, 2005): 72.

"Ciombination Therapy for Chronic Hepatitis C May Cause Pancreatitis." Science Letter (Sept. 21, 2004): 23.

"Genetic Testing May Play Key Role in Management of Pancreatitis." Genomics & Genetics Weekly (Dec. 24, 2004): 179.

"Managing Acute and Chronic Pancreatitis." The Practitioner (Oct. 12, 2005): 672.

Munos, Abilio, and David A. Katerndahl. "Diagnosis and Management of Acute Pancreatitis." American Family Physician 62 (July 2000): 164-73.

ORGANIZATIONS

National Digestive Diseases Information Clearinghouse. 2 Information Way, Bethesda, MD 20892-3570.

OTHER

National Institute of Diabetes and Digestive and Kidney Diseases. 〈http://www.niddk.nih.gov/health/digest/pubs/pancreas/pancreas.htm〉.

The National Pancreas Foundation. 〈http://www.pancreasfoundation.org/diseases.html〉.