The Effect of Pancreatic Exocrine Insufficiency and Pancreatic Enzyme Replacement Therapy on Gut Microbiome Composition in Pancreatic Disease: A Prospective Cohort Study.

Confirm chronic pancreatitis on CROSS-SECTIONAL IMAGING, CT for late calcific disease, MRI/MRCP (with secretin where available) for earlier ductal and parenchymal change, EUS an acceptable alternative; per ACG 2020, "Diagnosis is made usually on cross-sectional imaging, with modalities such as endoscopic ultrasonography and pancreatic function tests playing a secondary role". Fecal elastase does NOT confirm chronic pancreatitis: it is a test of exocrine FUNCTION and is the appropriate initial test for the exocrine pancreatic insufficiency (EPI) that chronic pancreatitis causes, a consequence of the disease, not the diagnosis of it. A normal fecal elastase does not exclude chronic pancreatitis and a low one does not establish it. Per AGA 2023, fecal elastase must be run on a semi-solid or solid stool specimen; below 100 mcg/g is good evidence of EPI and 100-200 mcg/g is indeterminate (below 200 mcg/g is the cutoff commonly used to screen). Then manage with smoking and alcohol cessation, PERT for exocrine insufficiency titrated to symptoms, fat-soluble vitamin and bone surveillance, and individualized type 3c diabetes control, considering insulin early in patients with marked hyperglycemia or symptoms of insulin deficiency. Treat pain with a stepwise ladder from scheduled acetaminophen and neuromodulators to EUS-guided celiac plexus block and endoscopic/surgical intervention, referring early for surgery per ESCAPE 2020 in candidates with main pancreatic duct obstruction. Screen for PDAC per lifetime risk and pursue etiologic workup via TIGAR-O v2, including genetic testing and autoimmune pancreatitis evaluation.