Neutrophil gelatinase-associated lipocalin serum level: A potential noninvasive biomarker of endometriosis?

Neutrophil gelatinase-associated lipocalin (NGAL, also known as lipocalin-2) is an acute-phase protein expressed in many tissues and plays a role in cell proliferation, regulation, and epithelial-mesenchymal transformation. Therefore, this study aimed to investigate serum NGAL levels and endometrioma tissue expression in women with endometriosis. This cross-sectional study was conducted at a university hospital. The endometrioma group included 36 women who underwent ovarian cystectomy for endometrioma, which was compared with a control group (n = 36) of women who underwent ovarian cystectomy due to benign persistent cysts (follicle cyst, theca lutein cyst, and serous cystadenoma). NGAL levels were analyzed using both serum enzyme-linked immunosorbent assay analysis and immunohistochemical tissue staining. Serum C-reactive protein and CA-125 levels were also evaluated. NGAL serum levels were significantly higher in the endometrioma group than in the control group (P < .05). C-reactive protein and CA-125 levels were also significantly higher in the endometrioma group (P < .05) and were correlated with NGAL levels. Immunohistochemical staining for NGAL was also higher in the endometrioma group (P < .001). NGAL may be considered a potential noninvasive biomarker of endometriosis.