Chronic pancreatitis

Reviewed by Dr Alan Ogilvie, consultant physician and gastroenterologist

What is the pancreas?

The pancreas is a soft, elongated gland situated at the back of the upper abdominal cavity behind the stomach.

It is divided into the head (through which the common bile duct runs as it enters the duodenum) and the body (which extends across the spine and the tail), which is close to the left kidney and to the spleen. Because the pancreas lies at the back of the abdominal cavity, diseases of the pancreas may be difficult to diagnose.

What does the pancreas do?

The pancreas has two main functions:

it produces a series of enzymes which help in the digestion of food. Enzymes produced in the pancreas are important in the digestion of proteins, carbohydrates and, particularly, fats. Bicarbonate is also produced in large amounts to neutralise the acid produced by the stomach.

it produces a series of hormones which are important in maintaining a normal level of sugar in the blood. The best known of these hormones is insulin. Insulin deficiency of this hormone results in the development of diabetes. Another hormone (glucagon) helps to raise blood sugar, and several other hormones control intestinal function.

What is pancreatitis?

Any inflammation of the pancreas is called pancreatitis.

Acute pancreatitis results in severe inflammation of the gland and patients may be seriously unwell.

Chronic pancreatitis develops either as the result of repeated attacks of acute pancreatitis or as the result of other injuries to the pancreas (see below).

It is thought that the damage to the pancreas occurs as the result of digestive enzymes leaking into the pancreas and starting to digest it. This sets up inflammation, and when the inflammation settles, the scarring process distorts the pancreas making further attacks of inflammation likely. Thus a vicious cycle develops.

As a result of prolonged damage to the pancreas, the pancreas fails to produce enough digestive enzymes to permit adequate digestion of food. This leads to weight loss and the frequent passage of pale greasy stools which contain excess amounts of fat. Further, the destruction of the cells which produce insulin may lead to the development of diabetes.

What causes chronic pancreatitis?

The most common cause of chronic pancreatitis is long-term excessive alcohol consumption. There is a direct relationship between the amount of alcohol consumed and the risk of developing chronic pancreatitis.

Other causes include:

high levels of calcium in the blood

abnormalities in anatomy which are usually present at birth

cystic fibrosis

high blood fats (hypertriglyceridaemia)

in rare cases, some drugs can cause pancreatitis

in a number of cases no specific cause can be identified, a condition known as idiopathic pancreatitis.

What are the symptoms of chronic pancreatitis?

The symptoms are very variable.

Pain occurs in most patients at some stage of the disease. This may vary in intensity from mild to severe. It may last for hours or sometimes days at a time and may require strong painkillers to control it.

It often radiates through to the back and can sometimes be relieved by crouching forward. It is commonly brought on by food consumption and so patients may be afraid to eat. It is also commonly severe through the night.

The pain varies in nature, being gnawing, stabbing, aching or burning, but it tends to be constant and not to come and go in waves. It may sometimes burn itself out but can remain an ongoing problem.

The mechanism of the pain is unclear. It seems to be related to pancreatic activity since it is frequently caused by food, especially fatty or rich foods.

Some patients will have obstruction to the small ducts in the pancreas by small stones, and this is thought to cause back pressure and destruction of the pancreas. There is no relationship between the severity of the pain and the severity of the pancreatic inflammation.

The pain is often difficult to diagnose and can be mistaken for pain caused by virtually any other condition arising from the abdomen or lower chest.

It can be difficult to distinguish pain caused by pancreatitis from pain caused by a peptic ulcer, irritable bowel syndrome, angina pectoris, gallstones.

Diabetes is also a common symptom which affects over half of all patients with long-standing chronic pancreatitis.

Long-standing chronic inflammation results in scarring of the pancreas which destroys the specialised areas of the pancreas which produce insulin.

Deficiency of insulin results in diabetes. Diabetes causes thirst, frequent urination and weight loss. It may be possible in the early stages of chronic pancreatitis to treat the diabetes with tablets, but in the late stage of chronic pancreatitis, insulin injections are usually needed.

Diarrhoea occurs in just under half of patients. Normally, all the fat in food is broken down by enzymes from the pancreas and small intestine, and the fat is then absorbed in the small bowel. With a reduced level of digestive enzymes the fat is not absorbed. When the fat reaches the large intestine, it is partially broken down by the bacteria in the colon. This produces substances which irritate the colon and result in diarrhoea. The undigested fat also traps water in the faeces, resulting in pale, bulky, greasy stools which are difficult to flush away. They may make the water in the toilet look oily, smell offensive and may be associated with bad wind.

Weight loss occurs in virtually all patients with chronic pancreatitis. It is due to failure to absorb calories from food, and diabetes may also contribute to this. In addition, patients may be afraid to eat because eating brings on the pain. Depression is also common in chronic pancreatitis and this can also reduce appetite and lead to weight loss.

Jaundice (when patients develop yellow eyes and skin) occurs in about a third of patients with chronic pancreatitis. It is usually due to damage to the common bile duct which drains bile from the liver to the duodenum.

The common bile duct normally passes though the head of the pancreas. In long-standing chronic pancreatitis, the scarring in the head of the pancreas narrows the common bile duct.

Some degree of narrowing may occur in up to half the patients with chronic pancreatitis but when the narrowing is severe, it prevents the bile draining from the liver into the duodenum. It then spills back into the blood and the patient's eyes and skin become yellow. In addition, the stools become paler (since bile makes the stools brown) and the urine becomes dark (because it contains more bile than normal).

Vomiting after meals is a less common symptom but can occur as a result of severe pain. It may also be due to duodenal ulceration, which is often connected with chronic pancreatitis. In rare cases, the duodenum may be narrowed as a result of scarring secondary to chronic pancreatitis.

Vitamin and mineral deficiency. Prolonged passage of stools containing fat can result in low levels of calcium and magnesium in the blood. In addition, some vitamins may not be absorbed properly. This includes vitamins D and A.

How is pancreatitis diagnosed?

Chronic pancreatitis often causes no symptoms and may be discovered by accident during the course of investigation of symptoms not related to pancreatitis. For example, calcification in the pancreas may be seen on an X-ray of the abdomen performed for other reasons.

If your doctor suspects that you have chronic pancreatitis, then the first examination is likely to be an ultrasound scan of the abdomen. More detailed examinations include a CT scan of the abdomen, an MRI scan of the abdomen, ERCP and - very rarely - analysis of the composition of the juice secreted into the duodenum by the pancreas.

Ultrasound examination of the abdomen

This type of examination is identical to that performed in pregnant women to assess the growth of the baby. It uses a transponder to generate high-frequency sound waves that bounce back from the deep tissues and are detected by the transponder (transmitter and responder). It is a very safe technique and is widely used. It is performed by smearing some jelly over the upper abdomen and then moving the transponder across the skin of the upper abdomen.

However, because the pancreas lies at the back of the abdominal cavity and, therefore, a long way from the transponder, images of the pancreas may be difficult to obtain. Sometimes the problem is obesity, sometimes the pancreas is obscured by air within the intestines.

Even if the result of the ultrasound examination is normal, this does not rule out the possibility of chronic pancreatitis.

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