Neutrophil Gelatinase-Associated Lipocalin in Peritoneal Effluent: Evaluation in Peritoneal Dialysis Patients in Basal Condition

♦ Purpose: In the present study, we assessed expression of neutrophil gelatinase-associated lipocalin (NGAL) in peritoneal effluent (pNGAL) from peritoneal dialysis (PD) patients, and we evaluated factors that might affect its level in basal conditions.♦ Methods: Our cross-sectional study included all 69 patients on PD at our institution. We evaluated patient history, hydration status, residual renal function, indices of dialysis adequacy, peritoneal transport type, serum C-reactive protein, ferritin, serum NGAL (sNGAL) and pNGAL. Univariate and multivariate linear regression models were used to evaluate predictors of pNGAL.♦ Results: Of the study patients, 39 (56.5%) were men, and 54 (78.3%) were on continuous ambulatory PD. Median age in the group was 61 years [interquartile range (IQR): 46.5 - 71 years]. Median sNGAL was 487 ng/mL (IQR: 407 - 586 ng/mL), and median pNGAL was 35 ng/mL (IQR: 21 - 46 ng/mL). dNGAL correlated directly with weekly dialytic clearance of creatinine (ρ = 0.291, p = 0.02) and with sNGAL (ρ = 0.269, p = 0.031). The same variables were also independent predictors of pNGAL (β = 0.30 and 0.29 respectively, both p < 0.05) in multivariate analysis.♦ Conclusions: In our analysis, basal levels of pNGAL were influenced by sNGAL and by dialytic clearance of creatinine.Key words: NGAL, biomarkers, peritoneal effluentNeutrophil gelatinase-associated lipocalin (NGAL) is a granulocyte-secreted polypeptide that specifically blocks bacterial growth by interfering with bacterial siderophores (1). Its role as marker has been evaluated in several conditions, including acute and chronic kidney disease (CKD), infections, and cancers. Moreover, some studies showed that NGAL secretion can be induced in epithelial cells during inflammatory insult. Specifically, Leung and colleagues (2) demonstrated secretion of NGAL by peritoneal mesothelial cells in a small group of peritoneal dialysis (PD) patients and suggested the usefulness of NGAL in PD effluent (pNGAL) for the diagnosis of peritonitis.Conversely, serum NGAL (sNGAL) is known to be high in patients with CKD (3), and high sNGAL might be paralleled by high pNGAL in PD patients. Moreover, certain systemic conditions such as hydration status or systemic inflammation may affect sNGAL (4) and consequently pNGAL. To date, no study assessing the possible interference of PD modality and systemic conditions on pNGAL concentration has been reported.The aim of the present study was to evaluate the consistency of pNGAL in basal conditions for describing a peritoneal local process and to evaluate how PD and systemic conditions might affect pNGAL values.