Causes of Pancreatitis
The most common causes of acute pancreatitis are gallstones and alcohol, accounting for approximately 70-75% of cases, while chronic pancreatitis in Western countries is predominantly caused by excess alcohol consumption, with other important etiologies including genetic mutations, autoimmune disease, anatomic anomalies, and metabolic disorders 1.
Acute Pancreatitis Etiologies
Primary Causes (in order of frequency)
- Gallstones: Represent approximately 50% of acute pancreatitis cases 2
- Alcohol: Accounts for 20-25% of cases 2
- Drug-induced: Particularly thiopurines (azathioprine, 6-mercaptopurine) occurring in ~4% of treated IBD patients, typically within 3-4 weeks of treatment initiation 3. 5-ASA carries much lower risk 3
- Post-ERCP: Iatrogenic cause from endoscopic procedures 3
- Hypertriglyceridemia: Severe hypertriglyceridemia (≥1,000 mg/dL) causes acute pancreatitis in 14% of affected patients, though hypertriglyceridemia represents only 9% of all pancreatitis cases 4
Secondary and Less Common Causes
- Hypercalcemia 1
- Trauma 5
- Autoimmune pancreatitis (IgG4-related) 3
- Anatomic anomalies: Pancreas divisum, pancreatic duct obstruction 1
- Duodenal Crohn's disease: Direct extension or fistulizing disease 3
- Viral infections 2
- Idiopathic: Approximately 20% of cases, though this should only be accepted after vigorous investigation including at least two high-quality ultrasound examinations 2
Critical Diagnostic Pitfall
Do not accept "idiopathic" pancreatitis without excluding microlithiasis/biliary sludge - this is the most common cause of recurrent "idiopathic" acute pancreatitis 5. Endoscopic ultrasound is the most accurate test for detecting microlithiasis and should be pursued in recurrent cases 2.
Chronic Pancreatitis Etiologies
Primary Cause
- Alcohol: The dominant etiology in Western countries 1
- Heavy smoking: Increases risk of developing chronic pancreatitis 1
Other Important Causes
- Genetic mutations: Including CFTR (cystic fibrosis), PRSS1, SPINK1 1
- Autoimmune pancreatitis 1
- Pancreatic duct obstruction 1
- Hypercalcemia 1
- Hypertriglyceridemia 1
- Recurrent acute pancreatitis: Can progress to chronic pancreatitis through repeated inflammatory episodes 6
- Tropical pancreatitis: Occurs in tropical/subtropical countries, associated with young, undernourished patients with early diabetes development 1
- Idiopathic: Approximately 20% of cases 1
Essential Workup Algorithm
Initial Assessment (Acute Phase)
- Pancreatic enzymes (lipase preferred over amylase - more specific) 7
- Liver function tests (AST, ALT, bilirubin, alkaline phosphatase) 7, 2
- Fasting triglycerides 7, 2
- Serum calcium 7, 2
- Right upper quadrant ultrasound for gallstones 2
- Detailed medication history (especially thiopurines, 5-ASA) 3
- Alcohol consumption history 2
Recovery Phase Investigations
- Repeat biliary ultrasound if first was negative 2
- MRCP for ductal anatomy and anomalies 2
- Fasting lipid panel 2
- Viral antibody titers 2
Recurrent/Idiopathic Cases
- Endoscopic ultrasound: Most sensitive for microlithiasis and small stones 2
- Autoimmune markers (IgG4) 3
- Genetic testing in young patients or those with family history 1
- ERCP with bile sampling for crystals (only after EUS) 2
Important caveat: In patients with multiple risk factors (alcohol, smoking, genetic predisposition), chronic pancreatitis often has multifactorial etiology rather than a single cause 8.