## 3 Results
### Laboratory Parameters Evaluation  
We evaluated the white cell count in PDE (287.5 \(\times\) 10\({}^{6}\)/L, IQR 81.5-2860.5 \(\times\) 10\({}^{6}\)/L), quantitative peritoneal NGALs (171 ng/mL, IQR 96.2-286.7 ng/mL) and peritoneal NGALds (300 ng/mL, IQR 150-300 ng/mL) in our PD population. We noticed a positive linear correlation between NGALds and laboratory-based NGAL values in the peritoneal dialysis effluent ([PERSON]'s rho = 0.88, \(p\) < 0.01). Furthermore, we observed a positive correlation between peritoneal NGALds and white cell count in PDE ([PERSON]'s rho = 0.82, \(p\) < 0.01). In addition, we reported a positive linear correlation between peritoneal NGALds values and CRP ([PERSON]'s rho = 0.54, \(p\) = 0.02). Table 3 describes the different inflammatory profiles in the case and control groups. In particular, all standard inflammatory parameters, such as CRP, WBC count in blood, white cell count in PDE, and peritoneal laboratory-based NGAL were different in the two groups (_p_ = 0.01, \(p\) = 0.03, \(p\) = 0.01, and <0.01, respectively). Similarly, in PDE, the NGALds levels resulted in being elevated in PD patients with peritonitis (300 ng/mL, IQR 300-600) compared with patients without peritonitis (100 ng/mL, IQR 50-150) (_p_ < 0.01). In particular, in the peritonitis group, all subjects were characterized by peritoneal NGALds values \(\geq\) 300 ng/mL. On the contrary, in the control group, two patients had peritoneal NGALds values equal to 300 ng/mL; no one had peritoneal NGALds values equal to 600 ng/mL (Table 4). Furthermore, we split patients into two groups based on the value of white cell count in PDE. The values of peritoneal NGALds resulted in being significantly higher in PD patients (n = 17) with a peritoneal white cell count \(\geq\) 100 \(\times\) 10\({}^{6}\)/L (300 ng/mL, IQR 300-600 versus 100 ng/mL, IQR 37.5-150) (Figure 1a). All patients with peritoneal white cell count \(\geq\) 100 \(\times\) 10\({}^{6}\)/L had peritoneal NGALds \(\geq\) 300 ng/mL. Only one patient with peritoneal white cell count < 100 \(\times\) 10\({}^{6}\)/L had peritoneal NGALds equal to 300 ng/mL. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Gram Stain** &
\begin{tabular}{c} **Causative Organism of** \\ **Peritonitis** \\ \end{tabular} & **Percentage (\%)** \\ \hline Gram-negative & Acinetobacter & 6 \\ (24\%) & Pseudomonas & 18 \\ Sterile & & 11 \\ (11\%) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Case Group** & **Control Group** & \(p\) \\ \hline CRP mg/dL, median (IQR) & 5.8 (3.2\(-\)12.3) & 1.6 (1.2\(-\)2.5) & 0.01 a \\ WBC count in blood (10\({}^{9}\)/L), median (IQR) & 7.6 (5.9\(-\)10.7) & 5.5 (5.1\(-\)6.1) & 0.03 a \\ White cell count in PDE (10\({}^{6}\)/L), median (IQR) & 2.8 (0.5\(-\)4.7) & 0.7 (0.5\(-\)8.6) & 0.01 a \\ Peritoneal laboratory-based NGAL test (ng/mL), median (IQR) & 265 (198\(-\)517) & 80 (46\(-\)121) & 0.01 a \\ Peritoneal NGALds (ng/mL), median (IQR) & 300 (300\(-\)600) & 100 (50\(-\)150) & \textless{}0.01 a \\ median (IQR) & & \\ \hline \hline \end{tabular} Legend: CRP, C-reactive protein; WBC, white blood cell; PDE, peritoneal dialyaste effluent; NGAL, neutrophil gelatinase-associated lipocalin; NGALds, neutrophil gelatinase-associated lipocalin dipstick; values represent medians (IQR, interquartile range); a Mann–Whitney U test.  
\end{table} 
Table 3: Inflammatory biomarkers in PD patients with (case group) and without (control group) peritonitis. In addition, we split patients into two categories based on the value of the quantitative peritoneal NGAL. The values of the peritoneal NGALds resulted in being significantly higher in PD patients with peritoneal laboratory-based NGAL \(\geq\) 200 ng/mL (n = 17) (300 ng/mL, IQR 300-600 versus 100 ng/mL, IQR 50-150) (Figure 2). All patients with peritoneal laboratory-based NGAL \(\geq\) 200 ng/mL had peritoneal NGALds \(\geq\) 300 ng/mL.