Evaluation of angiopoietin-like protein 4 levels in patients with endometriosis

Objective: Endometriosis is a chronic inflammatory disorder lacking definitive laboratory diagnostic markers. Angiopoietin-like protein-4 (ANGPTL4) is a protein involved in the regulation of angiogenesis and inflammation. The aim of the present study was to evaluate serum and peritoneal fluid (PF) levels of ANGPTL4 to explore its potential role in the pathogenesis of endometriosis. Material and Methods: This prospective study included women with surgically confirmed endometriosis and age-matched healthy controls with similar demographic characteristics. Clinical and laboratory parameters, including serum ANGPTL4, anti-Müllerian hormone (AMH), and cancer antigen-125 (CA125) levels were compared between groups. In addition, PF ANGPTL4 levels were assessed in the endometriosis group. Results: Serum ANGPTL4 (512.65±46.91 vs. 177.60±11.84 ng/mL, p<0.001) and CA125 (53.52±6.05 vs. 20.10±3.18 U/mL, p<0.001) levels were significantly higher in endometriosis group. Serum ANGPTL4 positively correlated with the severity of pelvic pain and dyspareunia, serum CA125 level and PF ANGPTL4, and negatively correlated with AMH (r=0.743, p<0.001; r=0.624, p<0.001; r=0.444, p<0.001; r=0.841, p<0.001; and r=-0.380, p<0.001, respectively). Receiver operating characteristic analysis identified an optimal serum ANGPTL4 cut-off value of 188.61 ng/mL (area under the curve =0.755, sensitivity 75% and specificity 62.5%, positive predictive value 66.7%, and negative predictive value 71.4%). Conclusion: Serum ANGPTL4 levels were significantly higher in women with endometriosis and were associated with clinical and laboratory parameters. It may serve as a supportive biomarker in the clinical assessment of endometriosis.