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Neutrophil Gelatinase-Associated Lipocalin in Peritoneal Dialysis-Related Peritonitis: Correlation with White Blood
Grazia Maria Virzi1,2, Maria Mattiotti1,2, Sabrina Milan Manani1,2
1Department of Nephrology, Dialysis, and Transplant, St Bortolo Hospital, Vicenza, Italy.
Introduction:
The present study aimed to monitor peritoneal neutrophil gelatinase-associated lipocalin (pNGAL) during peritonitis episodes and to enhance its diagnostic value by evaluating pNGAL at scheduled times in parallel with white blood cell (WBC) count. In addition, we investigated possible correlations between pNGAL and the etiology of peritonitis, evaluating it as a possible marker of the clinical outcome.
Methods:
Twenty-two patients with peritoneal dialysis (PD)-related peritonitis were enrolled. Peritonitis was divided into Gram-positive, Gram-negative, polymicrobial, and sterile. WBC count and neutrophil gelatinase-associated lipocalin (NGAL) in PD effluent were measured at different times (days 0, 1, 5, 10, 15, and/or 20 and 10 days after antibiotic therapy discontinuation). NGAL was measured by standard quantitative laboratory-based immunoassay and by colorimetric NGAL dipstick (NGALds) (dipstick test).
Results:
We found strong correlations between peritoneal WBC, laboratory-based NGAL, and NGALds values, both overall and separated at each time point. On day 1, we observed no significant difference in WBC, both NGALds (p = 0.3, 0.9, and 0.2) between Gram-positive, Gram-negative, polymicrobial, and sterile peritonitis. No significant difference has been found between de novo versus relapsing peritonitis for all markers (p > 0.05). We observed a parallel decrease of WBC and both NGAL in patients with favorable outcomes. WBC count and both pNGAL resulted higher in patients with negative outcomes (defined as relapsing peritonitis, peritonitis-associated catheter removal, peritonitis-associated hemodialysis transfer, peritonitis-associated death) at day 10 (p = 0.04, p = 0.03, and p = 0.05, respectively) and day 15 (p = 0.01, p = 0.04, and tendency for p = 0.005). There was a tendency toward higher levels of WBC and NGAL in patients with a negative outcome at day 5. No significant difference in all parameters was proven at day 1 (p = 0.3, p = 0.9, p = 0.2) between groups.
Conclusion:
This study confirms pNGAL as a valid and reliable biomarker for the diagnosis of PD-peritonitis and its monitoring. Its trend is parallel to WBC count during peritonitis episodes, in particular, patients with unfavorable outcomes.
Insights
Peritoneal neutrophil gelatinase-associated lipocalin (pNGAL) effectively monitors peritoneal dialysis-related peritonitis, mirroring white blood cell (WBC) trends. Elevated pNGAL levels indicate unfavorable outcomes in peritonitis patients.
Area of Science:
- Nephrology
- Clinical Chemistry
- Infectious Diseases
Background:
- Peritonitis is a serious complication of peritoneal dialysis (PD).
- Current diagnostic methods for PD-related peritonitis may require enhancement for timely and accurate monitoring.
- Neutrophil gelatinase-associated lipocalin (NGAL) shows potential as an inflammatory marker.
Purpose of the Study:
- To monitor peritoneal neutrophil gelatinase-associated lipocalin (pNGAL) during peritonitis episodes.
- To evaluate pNGAL's diagnostic value alongside white blood cell (WBC) count.
- To investigate correlations between pNGAL, peritonitis etiology, and clinical outcomes.
Main Methods:
- Twenty-two patients with PD-related peritonitis were enrolled.
- Peritoneal fluid samples were analyzed for WBC count and NGAL levels at multiple time points using immunoassay and a dipstick test (NGALds).
- Peritonitis was categorized by etiology (Gram-positive, Gram-negative, polymicrobial, sterile).
Main Results:
- Strong correlations were observed between peritoneal WBC, laboratory NGAL, and NGALds.
- No significant differences in WBC or NGAL were found on day 1 across different peritonitis etiologies or between de novo and relapsing cases.
- WBC and pNGAL levels decreased in patients with favorable outcomes and remained elevated in those with unfavorable outcomes at later time points (days 10 and 15).
Conclusions:
- pNGAL is a valid and reliable biomarker for diagnosing and monitoring PD-peritonitis.
- pNGAL trends parallel WBC counts during peritonitis.
- Elevated pNGAL levels are associated with unfavorable clinical outcomes in PD-peritonitis patients.
