A 38-year-old man presents to the emergency department with acute onset epigastric pain radiating to the back, associated with nausea and vomiting. Serum lipase is elevated at 8 times the upper limit of normal. What is the most common cause of acute pancreatitis in this patient?

Explanation

## Most Common Causes of Acute Pancreatitis **Key Point:** Gallstones account for approximately 40–50% of acute pancreatitis cases in developed countries, making it the single most common etiology globally. ### Epidemiology of Acute Pancreatitis Causes | Cause | Prevalence (%) | Geographic Variation | Key Features | |-------|----------------|----------------------|---------------| | **Gallstones** | 40–50 | Higher in developed nations | Female, age >40, obesity, rapid onset | | **Alcohol** | 25–35 | Higher in developed nations | Male predominance, chronic use history | | **Idiopathic** | 10–15 | Universal | No identifiable cause despite workup | | **Hypertriglyceridemia** | 1–4 | Universal | TG >1000 mg/dL, familial lipemia | | **Medications** | 0.5–2 | Universal | Temporal relationship to drug initiation | | **Trauma** | 1–3 | Universal | Post-ERCP, blunt injury, post-surgical | **High-Yield:** In India and South Asia, gallstones remain the leading cause, followed by alcohol in urban populations. Idiopathic pancreatitis is more common in Asian cohorts than Western series. ### Pathophysiology of Gallstone-Induced Pancreatitis Gallstones cause acute pancreatitis via: 1. **Mechanical obstruction** of the pancreatic duct at the ampulla of Vater 2. **Increased intraductal pressure** → acinar cell injury and enzyme activation 3. **Transient biliary reflux** → trypsinogen activation within the pancreas 4. Most attacks resolve within 24–48 hours as the stone passes into the duodenum **Clinical Pearl:** Gallstone pancreatitis typically presents with **sudden-onset pain** in a patient with biliary risk factors (female, fat, forty, fertile). Alcohol-induced pancreatitis usually has a more insidious onset with a history of chronic heavy drinking. **Warning:** Do not confuse the most common cause globally (gallstones) with the most common cause in chronic pancreatitis (alcohol). In acute pancreatitis, gallstones dominate; in chronic pancreatitis, alcohol is the leading cause.