Diagnostic Approach to Acute Pancreatitis

Primary Diagnostic Tests

The American College of Gastroenterology recommends serum lipase as the preferred laboratory test for diagnosing acute pancreatitis, with a cutoff value of three times the upper limit of normal providing optimal diagnostic accuracy 1, 2
Serum amylase can be used but is less specific and has a shorter diagnostic window than lipase, with a recommended cutoff value of greater than three times the upper limit of normal 3, 4, 5

Liver function tests, including bilirubin, AST, ALT, and alkaline phosphatase, are used to evaluate for biliary etiology 2
Serum triglycerides levels >11.3 mmol/L (>1000 mg/dL) indicate hypertriglyceridemia-induced pancreatitis 1, 3, 6
Serum calcium is used to evaluate for hypercalcemia as a potential cause 1, 2
C-reactive protein (CRP) levels ≥150 mg/L at 48-72 hours can predict severe acute pancreatitis 1, 6
Hematocrit >44% represents an independent risk factor for pancreatic necrosis 1, 6
Blood urea nitrogen >20 mg/dL is an independent predictor of mortality 1, 6
Procalcitonin is the most sensitive test for detecting pancreatic infection, with low values being strong negative predictors of infected necrosis 1, 6

Initial laboratory evaluation should include serum lipase (preferred) or amylase, complete blood count with hematocrit, comprehensive metabolic panel including BUN and calcium, and liver function tests 1, 2, 3
If lipase or amylase is >3x upper limit of normal, diagnosis of acute pancreatitis is confirmed, and etiology workup and severity assessment should be performed 1, 2
Serial CRP measurements, hematocrit, and BUN measurements are used for monitoring disease progression 1, 6
Procalcitonin is used if infection is suspected 1, 6