Laboratory Orders in Acute Pancreatitis
Order serum lipase (≥3× upper limit of normal for diagnosis), complete metabolic panel, liver function tests, serum triglycerides, serum calcium, complete blood count, and C-reactive protein at 48 hours for severity assessment. 1, 2
Initial Diagnostic Laboratory Tests
Primary Diagnostic Test
- Serum lipase is the preferred first-line test with a diagnostic threshold of ≥3 times the upper limit of normal, demonstrating superior sensitivity (79-91%) compared to amylase (62%) and remaining elevated longer (8-14 days versus 3-7 days) 1, 2
- Ordering both lipase and amylase together provides no diagnostic advantage and is unnecessary 1
- Lipase rises within 4-8 hours of pancreatic injury, peaks at 24 hours, making it ideal for early diagnosis 1
Etiologic Workup (Order at Admission)
- Liver function tests (bilirubin, AST, ALT, alkaline phosphatase) to evaluate for gallstone etiology and biliary obstruction 1, 2
- Serum triglycerides with levels >1000 mg/dL definitively indicating hypertriglyceridemia-induced pancreatitis 1, 2, 3
- Critical caveat: Triglycerides must be measured early as levels decrease rapidly with fasting and IV fluids 3
- Serum calcium to identify hypercalcemia as a causative factor 1, 2
Baseline Assessment
- Complete blood count for white blood cell elevation 1
- Complete metabolic panel including renal function and glucose 4, 5
Severity Assessment Laboratory Tests
Timing-Specific Markers
- C-reactive protein (CRP) at 48 hours with CRP ≥150 mg/L predicting severe disease 6, 1, 2
- CRP is unreliable before 48 hours after symptom onset 6
- APACHE II score should be calculated at admission and repeated at 24 hours using worst values, with a cutoff of 8 indicating severe disease 6, 2
Progressive Assessment Timeline
- At admission: Clinical evaluation of cardiovascular/respiratory/renal compromise, body mass index, APACHE II score 6
- At 24 hours: Repeat APACHE II score, Glasgow score (incomplete until 48 hours), CRP measurement may be useful depending on symptom onset 6
- At 48 hours: Glasgow score (≥3 indicates severity), CRP >150 mg/L, documentation of persistent organ failure 6, 2
Special Considerations for This Patient
Anticoagulation Context (Apixaban)
- Coagulation studies should be considered given apixaban use and potential need for procedures, though not specifically mentioned in pancreatitis guidelines, this is standard practice when bleeding risk or invasive procedures are anticipated
- Monitor for signs of bleeding complications given the inflammatory state and anticoagulation
Additional Testing Based on Clinical Course
- Serum IgG4 level (>280 mg/dL diagnostic) only if autoimmune pancreatitis is suspected 1
- Daily enzyme measurements have no value in assessing clinical progress and should be discouraged 7
Important Pitfalls to Avoid
- Do not rely on enzyme elevation degree to assess severity—patients can have severe pancreatitis with modest enzyme elevations 2
- Do not delay triglyceride measurement—levels fall rapidly with treatment, potentially missing hypertriglyceridemia as the etiology 3
- Do not use clinical assessment alone—it will misclassify approximately 50% of patients and must be supported by objective measures 6, 2
- Do not order imaging for diagnosis if lipase is diagnostic—reserve CT/MRI for diagnostic uncertainty or failure to improve clinically 8