Clinical Overview: Ranson's Criteria
Ranson's Criteria is a historic, widely taught clinical prediction rule developed in 1974 to estimate the mortality risk of acute pancreatitis. Pancreatitis is a severe inflammation of the pancreas, most commonly caused by gallstones or heavy alcohol use. When severe, the pancreas literally begins to digest itself, leading to systemic inflammation, organ failure, and death.
Because acute pancreatitis can look mild on day one but become rapidly fatal by day three, John Ranson identified 11 objective laboratory criteria that predict whether the patient will experience a mild or severe clinical course.
The 48-Hour Evaluation
A major limitation of Ranson's Criteria is that it requires two separate sets of data taken exactly 48 hours apart:
At Admission (0 Hours):
- Age > 55 years
- White Blood Cell Count > 16,000 /mm³
- Blood Glucose > 200 mg/dL
- Serum AST > 250 U/L
- Serum LDH > 350 U/L
At 48 Hours Post-Admission:
- Hematocrit fall > 10% (indicating internal bleeding or third-spacing)
- BUN rise > 5 mg/dL (indicating kidney failure from dehydration)
- Serum Calcium < 8 mg/dL (calcium is consumed by dying fat tissue, a process called saponification)
- pO2 < 60 mmHg (indicating lung failure/ARDS)
- Base Deficit > 4 mEq/L (indicating metabolic acidosis)
- Estimated Fluid Sequestration > 6 Liters
Formula Breakdown
Each positive criterion grants 1 point.
Ranson's Score = Admission Criteria (5) + 48-Hour Criteria (6)
- Score 0-2: Mild pancreatitis. Mortality < 1%.
- Score 3-4: Severe pancreatitis. Mortality ~15%.
- Score 5-6: Severe pancreatitis. Mortality ~40%.
- Score 7-11: Fulminant pancreatitis. Mortality approaches 100%.
Disclaimer: While historically important, Ranson's Criteria has largely been replaced in modern practice by scoring systems that don't require waiting 48 hours, such as the APACHE II score or the BISAP score.