The Diagnose Value Of Neutrophil Gelatinase-associated Lipocalin(NGAL) In Peritoneal Dialysis Effluent For Peritoneal Dialysis Related Peritonitis

Objective: To investigate the predictive value of diagnosis for peritoneal drainage fluid NGAL(p-NGAL) on peritoneal dialysis related peritonitis(PDRP) and analysis of p-NGAL in bacteria culture for G~+ bacteria,Gbacteria and diagnostic value of culture negative group, discuss on the diagnostic value of p-NGAL combined with p-WBC in diagnose bacterial peritonitis. Methods: Use case-control study, case group is 76 cases of PDRP patients, control group is 80 cases of common peritoneal dialysis(PD) patients at routine follow-up of our hospital’ peritoneal dialysis center. The diagnostic criteria of PDRP reference the standard of International Society for peritoneal dialysis. Primary collected testing index is p-NGAL、 p-WBC、 p-CRP、 b-CRP 、b-WBC, the time is General PD patients on the same day, PDRP patients are diagnosis of PDRP admission day, antibiotic treatment for 7 days and antibiotic treatment for 14 days. Non normal continuous variable use median and four points interval to describe, Comparison of differences among variables use U test. Biomarkers predicting the role of PDRP, Using ROC curve analysis curve area to evaluate and analysis its sensitivity and specificity. Results: During the 13 month study period, 76 patients with PDRP and 80 patients with PD,which b-WBC(p<0.001),b-CRP(p<0.001),p-CRP(p<0.001),p-WBC(p<0.001)and p-NGAL(p<0.001)have statistical difference. PDRP patients’ p-NGAL median concentration is higher about 9 times than normal PD patients, PDRP patients’ p-WBC median concentration is higher about 7 times than normal PD patients. The concentration of the p-WBC and p-NGAL decreased significantly with the improvement of PDRP. In PDRP patients,p-WBC and p-NGAL are significant positive correlation, r=0.666( p<0.001); p-CRP and p-WBC also the same, r=0.344(p<0.001). ROC curve analysis with p-WBC as the gold standard, the AUC of p-NGAL is 0.963(p<0.001), when its cut off value is 66ng/ml, which sensitivity and specificity of diagnosis PDRP positive is 100% and 78.75%,respectively(95%confidence interval Confidence interval 0.920-0.986).However, the AUC of b-WBC,b-CRP,p-CRP is 0.709(p<0.001),0.837(p<0.001)and 0.770(p<0.001), respectively. ROC curve analysis with bacteria culture as the gold standard, the AUC of G~+ bacteria, p-NGAL and P-WBC is 0.961(p<0.001) and 0.976(p<0.001), respectively; the AUC of G~- bacteria, p-NGAL and P-WBC is 0.972(p<0.001) and 0.991(p<0.001), respectively. In PDRP of bacterial culture positive, the AUC of combined p-WBC and p-NGAL is 0.991(p<0.001), the AUC of p-NGAL and P-WBC is 0.965(p<0.001) and 0.982(p<0.001). Conclusions: These results identify p-NGAL as a reliable biomarker for diagnosing PDRP. Diagnostic value of p-NGAL in the diagnosis of bacterial culture for G~+ bacteria, G~- bacteria equivalent to p-WBC. We also found that P-NGAL combined with p-WBC can better diagnose PDRP, and may cause p-WBC diagnostic threshold down in bacterial peritonitis of peritoneal dialysis patients(100*106/L).