NLR and Acute Pancreaatitis - Front Med 2026

#### Overview

The neutrophil-to-lymphocyte ratio (NLR) is a simple, cost-effective biomarker derived from routine blood tests. It measures the ratio of neutrophils (a type of white blood cell involved in inflammation) to lymphocytes (white blood cells associated with immune regulation). NLR has gained attention as a potential early predictor of severity, complications, and mortality in acute pancreatitis (AP).

#### Clinical Utility in Acute Pancreatitis

NLR has been systematically reviewed and analysed for its role in predicting outcomes in acute pancreatitis. It is particularly useful during the first 24–48 hours after hospital admission, a critical window for risk stratification. Key findings from the systematic review include:

1. **Prediction of Severe Disease**:

• Elevated NLR at admission is consistently associated with a higher likelihood of severe acute pancreatitis (SAP), which often requires intensive care.
• NLR dynamics (changes over time) during day 1 and day 2 improve the ability to identify patients at risk of persistent organ failure (POF).

2. **Identification of Infectious Complications**:

• NLR has shown utility in predicting infection-related complications, such as infected pancreatic necrosis (IPN), which is a serious condition requiring timely intervention.

3. **Mortality Risk**:

• An admission NLR greater than 12 has been associated with in-hospital mortality, making it a valuable tool for identifying patients with a poor prognosis.

4. **Discriminative Performance**:

• NLR demonstrates acceptable sensitivity and specificity for early triage decisions, making it a practical option for emergency departments.
• It remains clinically useful when combined with other scoring systems (e.g., APACHE II, BISAP) or laboratory markers (e.g., procalcitonin, CRP).

#### Advantages of NLR

• **Accessibility**: NLR can be calculated from routine blood tests, making it readily available without additional costs or delays.
• **Reproducibility**: It is a simple and reliable measurement.
• **Dynamic Monitoring**: NLR can be tracked over time to assess changes in inflammatory status, which is crucial for managing acute pancreatitis.

#### Limitations and Considerations

• **Time-Specific Thresholds**: The predictive accuracy of NLR depends on the timing of measurement (e.g., admission, 24 hours, 48 hours). Fixed thresholds may not account for dynamic changes.
• **Etiological Factors**: The performance of NLR may vary based on the underlying cause of pancreatitis (e.g., biliary pancreatitis vs. hypertriglyceridemia).
• **Integration with Other Tools**: While NLR is valuable, it is most effective when used alongside validated clinical scores and other biomarkers.

#### Recommendations

• The use of NLR for early triage in acute pancreatitis is recommended, particularly in the first 48 hours.
• Time-specific thresholds should be locally calibrated to optimize sensitivity and specificity.
• Combining NLR with clinical scores and other laboratory markers (e.g., CRP, procalcitonin) can enhance decision-making accuracy.

#### Systematic Review Registration

The systematic review evaluating NLR in acute pancreatitis is registered with PROSPERO (CRD420251169592), ensuring transparency and methodological rigour.

### Conclusion

The neutrophil-to-lymphocyte ratio (NLR) is a promising biomarker for early risk stratification in acute pancreatitis. Its ability to predict severe disease, persistent organ failure, infectious complications, and mortality makes it a valuable tool for guiding clinical decisions during the critical early phase of hospitalisation. Future studies should focus on refining thresholds, validating findings across different populations, and integrating NLR into composite predictive models.