35. Laboratory diagnosis of chronic pancreatitis

Chronic pancreatitis is characterised by chronic inflammation of the pancreas with replacement of normal parenchyme by fibrotic scar tissue, which causes chronic abdominal pain and pancreatic insufficiency. It is an ongoing, progressive pathologic response to pancreatic injury. In most cases, chronic pancreatitis is caused by having multiple episodes of acute pancreatitis. The disease progresses gradually from a single episode of acute pancreatitis to relapsing episodes of acute pancreatitis to chronic pancreatitis.

Diagnosis and evaluation

Contrast CT or MRCP will show pancreatic atrophy and parenchymal calcification. If other investigations are not diagnostic, pancreatic functional diagnostics may be used. The most likely underlying cause of the chronic pancreatitis must be sought, based on history of exposure to risk factors, lab tests, and possibly genetic testing. Unlike in acute pancreatitis, amylase and lipase are rarely elevated.

Functional diagnostics of pancreatic insufficiency

Direct pancreatic functional testing

IV administration of pancreas-stimulating hormones (secretin or cholecystokinin) stimulates the secretion of pancreatic juice. This fluid can be collected by an oroduodenal tube or an upper endoscope and measured. A bicarbonate concentration of this fluid of < 80 mEq/L is diagnostic of exocrine pancreatic insufficiency.

Direct tests are more sensitive than indirect tests, but also more expensive and difficult to perform.

Indirect pancreatic functional testing

Measuring the amount of elastase in the stool can be used for diagnosis of exocrine pancreatic insufficiency. Impaired glucose tolerance or diabetes mellitus may be due to endocrine pancreatic insufficiency. Increased content of lipids in the stool may indicate lipase deficiency due to pancreatic insufficiency.