What labs are used for prognosis in acute pancreatitis?

Prognostic Laboratory Markers in Acute Pancreatitis

C-reactive protein (CRP) is the most valuable and widely available laboratory marker for predicting severity in acute pancreatitis, with levels >150 mg/L at 48 hours after disease onset indicating severe disease. 1, 2

Primary Prognostic Laboratory Markers

C-reactive Protein (CRP)

• Gold standard among biochemical markers for severity prediction 3, 4
• Peak level >210 mg/L in first four days or >150 mg/L at 48 hours indicates severe disease 1, 2
• Overall accuracy of approximately 80% 1
• Despite delayed increase (peaks at 48-72 hours), remains most reliable and widely available marker 3, 4
• Can be combined with Glasgow criteria for improved prognostication 1

Procalcitonin (PCT)

• Most sensitive laboratory test for detection of pancreatic infection 2
• Low values strongly predict absence of infected necrosis 2
• Useful for monitoring disease progression 3
• Shows significant differences between mild and severe cases on admission 3

Multifactor Scoring Systems

APACHE II Score

• Preferred scoring system according to AGA Institute 1
• Score ≥8 indicates severe disease 1
• Score ≥6 has 95% sensitivity for complications but only 50% positive predictive value 1
• Useful for initial assessment and ongoing monitoring in severe cases 1, 2
• Can be calculated at admission and daily for disease progression monitoring 1, 2

Glasgow/Imrie Scoring System

• Validated in UK population 1
• Three or more positive criteria within 48 hours indicates severe disease 1
• 70-80% accuracy in predicting severity 1
• Recommended to be used alongside CRP measurement 1

Other Useful Laboratory Markers

Interleukin-6 (IL-6)

• Promising early marker for severity prediction 5, 3, 4
• Rises earlier than CRP, allowing earlier severity prediction 3, 4
• Not yet widely available in routine clinical practice 6

Trypsinogen Activation Peptide (TAP)

• Shows significant differences between mild and severe cases on admission 3
• Can predict severity within 12-24 hours of onset 6
• Limited by availability in routine clinical settings 6

Serum Amyloid A

• Reliable predictor with persistently elevated levels in severe disease 3

Phospholipase A2

• Elevated levels persist in severe disease 3

Laboratory Tests for Diagnosis vs. Prognosis

• Serum lipase is preferred over amylase for diagnosis (higher sensitivity and longer diagnostic window) 2, 6
• Lipase elevation >3 times upper limit of normal is most consistent with acute pancreatitis 1
• Once diagnosis is established, daily enzyme measurements have no value in assessing clinical progress or prognosis 6
• Initial laboratory tests should include amylase/lipase, triglycerides, calcium, and liver chemistries 1

Practical Approach to Laboratory Assessment

1. At admission:

   • Measure serum lipase/amylase for diagnosis
   • Calculate APACHE II score for initial severity assessment
   • Consider IL-6 or TAP if available for early severity prediction

2. At 48 hours:

   • Measure CRP (>150 mg/L indicates severe disease)
   • Complete Glasgow scoring (≥3 criteria indicates severe disease)
   • Reassess APACHE II score

3. For ongoing monitoring:

   • Serial APACHE II scores to track disease progression
   • Procalcitonin to detect pancreatic infection
   • CRP to monitor inflammatory response

Limitations and Caveats

• No single marker can predict all patients who will develop complications 1
• Many patients initially classified as severe will have uncomplicated recovery 1
• Laboratory markers should be used as an adjunct to clinical judgment and imaging 1, 7
• The change in probability from pre-test to post-test gives the best indication of a test's clinical usefulness 7
• Combination of markers may improve prognostic accuracy 7, 4

Remember that laboratory markers should be integrated with clinical assessment and imaging studies (particularly contrast-enhanced CT after 72 hours) for optimal prognostication and management of acute pancreatitis 1, 2.