Neutrophil gelatinase-associated lipocalin as a predictor of pre-eclampsia: A systematic review and meta-analysis

Background Protein neutrophil gelatinase-associated lipocalin (NGAL) has been associated with kidney injury and inflammatory conditions. In particular, several studies have found an association between maternal blood and urine levels and the development of pre-eclampsia.Objectives To examine whether maternal blood and urine levels of NGAL are good predictors of pre-eclampsia.Search strategy The authors searched MEDLINE databases via PubMed, Embase, Scopus, Scielo, Google Scholar, PROSPERO International Prospective Register of Systematic Reviews, and the Cochrane Central Register of Controlled Trials.Selection criteria The authors included case-control observational clinical studies comparing protein levels of NGAL in serum and urine in women with pre-eclampsia with uncomplicated pregnancies. Only studies where the collection of blood or urine was peformed before the occurrence of pre-eclampsia were selected.Data collection and analysis The primary outcome was the difference in NGAL levels in blood or urine between women with and without pre-eclampsia.Results Seven studies in total were included: five studies measuring NGAL in blood and two in urine. Regarding the serum studies, 315 patients were included as cases and 540 as controls. Higher NGAL in maternal blood during all three trimesters together was associated with pre-eclampsia; the standardized mean difference was 1.15 ng/mL (95% confidence interval, 0.92-1.39; P < 0.01). Regarding the urine studies, 39 patients were included as cases and 220 as controls. There was no statistically significant difference between patients with pre-eclampsia and controls regarding urine NGAL.Conclusions NGAL in maternal blood is higher in patients who later develop pre-eclampsia compared with controls and could be used as a potential predicting test in the routine clinical setting.