What causes pancreatitis?

Causes of Pancreatitis

The most common causes of acute pancreatitis are gallstones (approximately 50% of cases) and alcohol abuse (20-25% of cases), with various other etiologies accounting for the remaining cases. 1

Primary Causes of Pancreatitis

Common Causes

• Gallstones: The leading cause, responsible for about 50% of cases
• Alcohol abuse: Second most common cause (20-25% of cases)
• Medications: Particularly:
  • Thiopurines (azathioprine/6-mercaptopurine) - occurs in approximately 4% of IBD patients treated with these drugs 2
  • 5-ASA compounds (less common than thiopurines) 2
  • Other medications: valproic acid and didanosine 1

Metabolic Causes

• Hypertriglyceridemia: Especially when levels exceed 1000 mg/dL 1
• Hypercalcemia: Can trigger pancreatic inflammation 1

Anatomical and Structural Causes

• Pancreas divisum: A congenital anomaly detectable by MRCP 1
• Sphincter of Oddi dysfunction: Requires specialized testing like biliary manometry 1
• Post-ERCP pancreatitis: Procedural complication 2, 1
• Post-surgical pancreatitis: Especially after abdominal operations 1

Inflammatory and Autoimmune Causes

• Inflammatory Bowel Disease (IBD): Especially Crohn's disease with duodenal involvement 2, 1
• Autoimmune pancreatitis: IgG4-related disease 2, 1
• Vasculitis: Can affect pancreatic blood vessels 1

Infectious Causes

• Viral infections: Including mumps and Coxsackie B4 1
• Helicobacter pylori infection: Associated with 1.5 times increased risk 2
• Rare bacterial infections: Such as Mycoplasma pneumoniae 3

Special Considerations in IBD Patients

IBD patients have unique considerations regarding pancreatitis:

• Two IBD-specific forms of acute pancreatitis exist 2:

  1. Related to shared pathogenic pathways: Autoimmune pancreatitis, idiopathic pancreatitis, granulomatous pancreatitis, and pancreatitis associated with PSC
  2. Related to IBD management: Drug-induced, biliary pancreatitis, secondary to duodenal Crohn's disease, post-ERCP pancreatitis

• Medication-induced pancreatitis in IBD patients:

  • Azathioprine/6-mercaptopurine-induced pancreatitis is dose-independent and typically occurs within 3-4 weeks of treatment 2
  • Patients carrying the HLA-DQA102:01-HLA-DRB107:01 haplotype are more susceptible 2
  • The risk is higher in Crohn's disease than ulcerative colitis 2

• Diagnostic challenges:

  • Abdominal pain from pancreatitis may be difficult to differentiate from active IBD 2
  • Asymptomatic elevated lipase is found in 7% of IBD patients 2, 1

Idiopathic Pancreatitis

Despite thorough investigation, approximately 10-20% of cases remain idiopathic 1. In these cases, repeat evaluations including:

• Multiple ultrasound examinations
• Fasting lipid profile
• Calcium levels
• Consideration of genetic testing in young patients with recurrent episodes

Risk Factors

Several factors increase the risk of developing pancreatitis:

• Non-O blood group: 1.4 times increased risk 2
• Diabetes mellitus: 1.4-2.2 times increased risk 2
• Obesity: 1.2-1.5 times increased risk 2
• Red meat intake: 1.1-1.5 times increased risk 2
• Tobacco use: Doubles the risk of pancreatic disease 2

Changing Epidemiology

The incidence of acute pancreatitis is increasing in many countries, possibly related to rising obesity rates which increase the likelihood of gallstone pancreatitis 4. However, mortality rates for acute pancreatitis are declining in many reports, though overall mortality remains around 5% 4.

Understanding the diverse causes of pancreatitis is essential for proper diagnosis, management, and prevention of recurrence in affected patients.