Tests
1st tests to order
computed tomography (CT) or magnetic resonance imaging (MRI)
Test
Either CT or MRI is recommended first-line for the diagnosis of chronic pancreatitis.[85]
Result
pancreatic calcifications, focal or diffuse enlargement of the pancreas, ductal dilation, and/or vascular complications
endoscopic ultrasonography (EUS)
Test
EUS should only be used if the diagnosis is in question after cross-sectional imaging is performed. It is invasive and lacks specificity.[85]
EUS affords a more detailed evaluation of the pancreatic parenchyma and ducts than abdominal ultrasound or CT, and is less invasive than endoscopic retrograde cholangiopancreatography.
Helps distinguish between chronic pancreatitis and intraductal neoplasms based on imaging features and the use of fine-needle aspiration, but EUS is imperfect.
A Brazilian consensus panel rated EUS as having high accuracy for diagnosis of chronic pancreatitis.[128] Sensitive for features of chronic pancreatitis but has unclear specificity for diagnosis of early chronic pancreatitis.
Interobserver agreements for features of chronic pancreatitis, however, are good for duct dilation and lobularity but poor for other features.[129]
Unless there are five or more equally weighted features of chronic pancreatitis present, the diagnosis should be considered possible or indeterminate and corroborated by additional functional and structural data and prospective follow-up. A “Rosemont” consensus panel proposed, however, that a diagnosis of chronic pancreatitis may require fewer than five EUS features when certain EUS features of chronic pancreatitis are assigned greater positive predictive value.[130] Prospective validation is required. Risks of EUS include perforation, infection, and bleeding.[110]
Result
ductal and parenchymal abnormalities
secretin-enhanced magnetic resonance cholangiopancreatography (s-MRCP)
Test
s-MRCP is suggested when the diagnosis of chronic pancreatitis is not confirmed following cross-sectional imaging with CR/MRI or EUS and clinical suspicion remains high.[85]
s-MRCP allows for better visualization of the main and side branch pancreatic ducts by stimulating the release of bicarbonate from the pancreatic duct cells.[111]
Result
abnormal exocrine function
Tests to consider
histological examination
Test
Suggested as the gold standard to diagnose chronic pancreatitis in high-risk patients when the clinical and functional evidence of chronic pancreatitis is strong, but diagnosis is inconclusive after cross sectional imaging with CT/MRI or EUS.[85]
Changes produced by chronic pancreatitis depend on disease severity and include an increase in connective tissue, inflammatory and fibrotic changes, loss of acini, and plugs of precipitated protein in the ductal tissue.
Ruling out malignancy is a major diagnostic problem, especially in patients with an enlarged pancreatic head. Exclusion of malignancy frequently requires surgical resection to ensure a reliable histopathologic examination. In 10% of patients, the diagnosis of pancreatic cancer is only established by histologic proof at the time of operation.
Result
increased connective tissue, inflammation, fibrosis, loss of acini, protein plugs in ducts
genetic testing
Test
Genetic testing is recommended in patients with clinical evidence of possible chronic pancreatitis in which the etiology is unclear, especially in younger patients.[85]
At minimum, patients with idiopathic chronic pancreatitis should be evaluated for PRSS1, SPINK1, CFTR, CTRC, CASR, and CPA1 gene mutations. Up to 50% of patients with idiopathic chronic pancreatitis have mutations of SPINK or the CFTR gene.[59][60]
Result
PRSS1; SPINK1; CFTR, CTRC, CASR, CPA1
indirect pancreatic function test (fecal elastase-1)
Test
All indirect pancreatic function tests have relatively high sensitivity and specificity in severe chronic pancreatitis with malabsorption. All are inaccurate for diagnosing mild to moderate pancreatic insufficiency.[114][115][131]
Fecal elastase-1 test is the initial test for diagnosing exocrine pancreatic insufficiency.[84] Test can be performed in patients on pancreatic enzyme replacement therapy.[84]
Fecal elastase-1 value of <100 micrograms/g of stool is suggestive of exocrine pancreatic insufficiency; values between 100 and 200 micrograms/g of stool are considered indeterminate for exocrine pancreatic insufficiency.[84] A fecal elastase-1 value of <50 micrograms/g may indicate severe exocrine pancreatic insufficiency.[84]
Reduced fecal elastase has only 58% specificity for exocrine pancreatic insufficiency in patients with type 1 diabetes mellitus.[132]
Result
a value of <100 micrograms/g of stool suggests exocrine pancreatic insufficiency
fecal fat
Test
This test is performed by administering 100 g fat per day and measuring the fecal fat excretion over 72 hours.
Increased fecal fat over 7 g/day is a late-stage manifestation of chronic pancreatitis.
Result
increased
steatocrit
Test
A rapid gravimetric method to measure stool fat. Past studies reported that when performed on samples from a 72-hour stool collection, steatocrit is as sensitive and specific as a 72-hour quantitative stool fat, and may be as accurate if performed on a 24-hour stool collection or random stool samples.[133] Others performed 72-hour fecal balance studies in patients with cystic fibrosis and reported that steatocrit was unreliable for predicting fecal fat excretion, but these patients had minimal increases in fecal fat excretion (all <10 grams/day).[134]
Result
increased
direct pancreatic function tests
Test
Most sensitive and specific test for diagnosing mild to moderate pancreatic insufficiency or chronic pancreatitis.[112][113]
Tests remain clinically useful for excluding chronic pancreatitis in patients with suspected early chronic pancreatitis but normal pancreatic imaging (97% negative predictive value).[135]
Pancreatic juice is collected with a gastroduodenal tube during exogenous hormone stimulation with cholecystokinin and/or secretin. One major concern with “simpler” endoscopic methods is that these tests do not aspirate gastric juice to prevent degradation and/or dilution of pancreatic juice lipase and bicarbonate, which leads to false positive tests.[136]
Helps differentiate pancreatic from nonpancreatic types of malabsorption.
Result
decreased function
IgG4 levels
therapeutic trial of corticosteroids
Test
A positive response suggests autoimmune pancreatitis. This test is an alternative to biopsy, but requires follow-up and should only be used by a specialist.[117]
Result
positive response in autoimmune pancreatitis
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