Causes of Acute Pancreatitis
The most common causes of acute pancreatitis are gallstones and alcohol abuse, but there are numerous other etiologies that must be considered when evaluating patients with this potentially life-threatening condition. 1, 2
Common Causes
Biliary Causes
- Gallstones/biliary lithiasis (most common cause, approximately 50% of cases) 1
- Microlithiasis (small gallstones that may be missed on conventional imaging)
- Biliary sludge
- Sphincter of Oddi dysfunction
- Ampullary or pancreatic tumors causing obstruction
- Juxtapapillary diverticulum 3
Toxic-Metabolic Causes
- Alcohol consumption (second most common cause, 20-25% of cases) 1
- Hypertriglyceridemia (especially levels >1000 mg/dL) 4
- Hypercalcemia (often associated with hyperparathyroidism) 3
Drug-Induced Pancreatitis
Class I Medications (strongest evidence)
- Azathioprine/6-mercaptopurine
- Valproic acid
- Didanosine
- Mesalamine/sulfasalazine
- Estrogens
- Furosemide
- Tetracycline
- Pentamidine
- Opiates 5
Class II Medications (moderate evidence)
- Acetaminophen
- Carbamazepine
- Enalapril
- Erythromycin
- Hydrochlorothiazide
- Interferon
- Lamivudine
- Octreotide 5
Infectious Causes
- Viral infections (mumps, hepatitis, coxsackievirus)
- Bacterial infections (Mycoplasma pneumoniae) 6
- Parasitic infections (causing papillary obstruction)
- Fungal infections 3
Mechanical/Structural Causes
- Post-ERCP (endoscopic retrograde cholangiopancreatography) 1
- Pancreas divisum
- Trauma (blunt abdominal trauma or surgical)
- Postoperative pancreatitis 3
Inflammatory/Autoimmune Causes
- Inflammatory bowel disease (especially Crohn's disease with duodenal involvement) 1
- Autoimmune pancreatitis (IgG4-related)
- Vasculitis 1
Genetic Causes
- Hereditary pancreatitis (PRSS1, SPINK1, CFTR mutations)
- Familial hypertriglyceridemia 3
Other Causes
- Idiopathic (approximately 10-20% of cases after thorough investigation) 1
- Pregnancy-related
- Scorpion venom
- Tropical pancreatitis (in certain geographic regions) 3
Diagnostic Approach
When evaluating a patient with acute pancreatitis, a systematic approach to identify the etiology should be followed:
Initial assessment: Obtain detailed history focusing on:
- Alcohol consumption patterns
- Medication use (especially Class I and II medications)
- Known gallstone disease
- Previous episodes of pancreatitis
- Family history of pancreatitis
- Recent procedures (ERCP)
- Symptoms of hyperlipidemia or hypercalcemia
Laboratory evaluation:
- Liver function tests (elevated transaminases suggest biliary etiology)
- Triglyceride levels (>1000 mg/dL suggests hypertriglyceridemia as cause)
- Calcium levels
- IgG4 levels (if autoimmune pancreatitis suspected)
Imaging studies:
- Abdominal ultrasound (first-line for gallstone detection)
- CT scan with contrast (for pancreatic morphology and complications)
- MRCP (for biliary and pancreatic duct evaluation)
- Endoscopic ultrasound (for microlithiasis, small tumors, and chronic changes)
Important Considerations
- In patients with recurrent "idiopathic" pancreatitis, at least two good-quality ultrasound examinations should be performed to rule out gallstones 1
- In patients over 50 years with first episode of acute pancreatitis, pancreatic tumors must be specifically ruled out 7
- Up to 7% of IBD patients may have asymptomatic elevated lipase without clinical pancreatitis 1
- Drug-induced pancreatitis is often overlooked and should be considered especially in elderly patients on multiple medications, HIV+ patients, and those on immunomodulating agents 5
By systematically evaluating these potential causes, the etiology of acute pancreatitis can be identified in the majority of cases, allowing for targeted treatment and prevention of recurrence.