What is the preferred diagnostic test between lipase (lipase) and urine trypsinogen-2 dipstick in pediatric pancreatitis?

Serum Lipase is the Preferred Diagnostic Test for Pediatric Acute Pancreatitis

Serum lipase should be the primary diagnostic test for pediatric acute pancreatitis, with urine trypsinogen-2 dipstick serving as a promising noninvasive alternative when collected within 24 hours of symptom onset. 1

Primary Recommendation: Serum Lipase

Lipase is recommended as the superior diagnostic biomarker for pediatric acute pancreatitis by the World Journal of Emergency Surgery guidelines. 1 The key advantages include:

• Higher sensitivity (79%) and specificity (89%) compared to amylase (72% sensitivity, 93% specificity) 2, 1
• Larger diagnostic window: Lipase rises within 4-8 hours, peaks at 24 hours, and remains elevated for 8-14 days, compared to amylase which normalizes in 3-7 days 2, 1
• Greater reliability: Lipase is more specific for pancreatic pathology, whereas amylase can be elevated in numerous non-pancreatic conditions including renal disease, appendicitis, acute cholecystitis, bowel obstruction, head injuries, and hepatic injuries 2, 1

The diagnostic threshold is ≥3 times the upper limit of normal, which provides optimal balance between sensitivity and specificity for acute pancreatitis. 3, 1

Urine Trypsinogen-2 Dipstick: A Promising Alternative

The urine trypsinogen-2 dipstick test (UTDT) represents a rapid, noninvasive bedside alternative with distinct advantages in pediatric populations:

Performance Characteristics

• Overall sensitivity: 68-82% and specificity: 94-100% for acute pancreatitis 2, 4, 5
• Timing-dependent performance: Sensitivity increases dramatically to 87-94% when urine samples are collected within 24 hours of admission 4, 6
• Excellent negative predictive value: In non-pancreatitis cases, UTDT consistently produces negative results with 100% specificity in the most recent pediatric study 4

Clinical Context

The most recent 2025 pediatric-specific study demonstrates that UTDT has 100% specificity in children, making it highly reliable for ruling in acute pancreatitis when positive. 4 This represents the first prospective evaluation specifically in pediatric patients and shows superior performance to earlier meta-analyses in adult populations. 4

Trypsinogen concentrations rise to high levels within a few hours and decrease within 3 days, providing a rapid early diagnostic window. 2, 1

Comparative Analysis

Why Lipase Remains First-Line

Despite the promising noninvasive nature of UTDT, lipase maintains superiority as the primary diagnostic test because:

• Established guideline support: Current guidelines from the World Journal of Emergency Surgery explicitly recommend lipase as the primary biomarker 1
• Slightly higher sensitivity: Lipase (79%) outperforms UTDT overall sensitivity (68-82%), though this gap narrows with early UTDT collection 2, 1, 5
• Longer diagnostic window: Lipase remains elevated for 8-14 days versus 3 days for trypsinogen, allowing diagnosis in delayed presentations 2, 1
• Universal availability: Lipase testing is standardized and available in all clinical laboratories, whereas UTDT requires validation through larger-scale studies 4

When UTDT May Be Preferred

The urine dipstick test offers specific advantages in pediatric settings:

• Noninvasive collection: Particularly valuable in children where blood draws are challenging and distressing 4
• Rapid bedside results: Provides immediate diagnostic information without laboratory processing time 2, 5
• Early presentation: When patients present within 24 hours of symptom onset, UTDT sensitivity approaches that of lipase (87% vs 79%) 4, 6

Critical Pitfalls to Avoid

Enzyme Levels Do Not Predict Severity

The degree of enzyme elevation does not correlate with disease severity. A patient with lipase 4 times normal can have severe pancreatitis while another with 20 times normal may have mild disease. 3, 1 No laboratory test, including serial enzyme measurements, is consistently accurate for predicting severity in acute pancreatitis. 2, 3, 1

Timing Considerations

• Early CT imaging (within 72 hours) may underestimate pancreatic necrosis and should be reserved for patients with predicted severe disease, organ failure, or inconclusive biochemical findings 3
• UTDT sensitivity drops significantly if urine is not collected within the first 24 hours of presentation 4, 6
• Lipase drawn on admission can exclude pancreatic injury with a negative predictive value of 99.8% 3

Additional Diagnostic Workup

In the absence of gallstones or significant alcohol history, measure serum triglyceride and calcium levels. 3, 1 Triglyceride levels >11.3 mmol/L (>1000 mg/dL) indicate hypertriglyceridemia as the etiology. 2, 3, 1

Practical Algorithm for Pediatric Pancreatitis Diagnosis

1. First-line test: Order serum lipase (≥3× upper limit of normal diagnostic threshold) 1
2. If blood draw is challenging or refused: Consider UTDT if patient presents within 24 hours of symptom onset 4
3. If UTDT is positive: High specificity (100%) confirms diagnosis; proceed with severity assessment and imaging 4
4. If UTDT is negative but clinical suspicion remains high: Obtain serum lipase, as UTDT sensitivity is only 68% overall 4, 5
5. Severity assessment: Use clinical parameters, APACHE II scores, and C-reactive protein ≥150 mg/L at day 3, not enzyme levels 2, 3, 1