Chronic pancreatitis causes pain, maldigestion and weight loss, and, as the disease progresses, diabetes and a set of complications. The features follow from the loss of parenchyma: the same process that destroys the enzyme-producing acinar cells eventually destroys the insulin-producing islet cells as well.
Pain
Pain dominates the early stage of the disease, when a lot of parenchymal tissue is still present. Its location and intensity vary between patients — it is mostly felt in the epigastric region and radiates to the back — and it can be intermittent or constant, with pain-free intervals. Over time the pattern usually changes from episodic to continuous, and eating can set it off, so patients may eat less to avoid the pain and lose weight as a result.
Pain does not correlate with the severity of the pancreatic damage. Some patients have imaging findings of extensive necrosis while they are still pain-free, and pain often lessens late in the disease, as inflammation and glandular tissue are lost.
Maldigestion and weight loss
Steatorrhea is the passage of light-coloured, foul-smelling faeces. It is caused by maldigestion: the failing gland no longer delivers enough digestive enzymes to break down fat, and the unabsorbed fat leaves in the stool. The malabsorption leads to malnutrition, and fat-soluble vitamin deficiency is common. About 65% of patients with chronic pancreatitis have a metabolic bone disorder such as osteopenia or osteoporosis, related largely to vitamin D deficiency.
The underlying problem is exocrine pancreatic insufficiency — the pancreas no longer makes enough enzymes to digest food. It becomes evident only when more than 80% of the exocrine gland is destroyed, which is why early disease is easy to miss; by the time it is overt, steatorrhea is present.
Diabetes and other complications
- Diabetes mellitus — the lifetime prevalence in chronic pancreatitis is more than 80%. It is driven by loss of insulin secretion rather than by insulin resistance, but the complications of diabetes in these patients, such as organ damage like neuropathy, are not that common.
- Osteoporosis and osteopenia — the malabsorption of vitamin D and calcium weakens bone.
- Splenic vein thrombosis — a clot in the splenic vein can lead to portal vein hypertension and consequent bleeding in the gastrointestinal tract.
Pancreatic cancer is an additional long-term risk of chronic pancreatitis.