Evaluation of Endoplasmic Reticulum Stress in Endometriosis Patients by Determination of Serum X-box Binding Protein 1 Levels

OBJECTIVE: To evaluate endoplasmic reticulum stress levels in the presence of endometriosis by comparing the serum X-box binding protein 1 (XBP-1) levels between endometriosis patients and a healthy control group. STUDY DESIGN: A total of 86 patients who were previously diagnosed with endometriosis with persistent endometriomas were included in the study group. Sixty healthy subjects were recruited to the control group. Serum XBP-1 levels were determined and pain symptoms were evaluated using visual analogue scale (VAS). RESULTS: The area under curve for XBP-1 levels in the study group was 91% (95% CI 0.860-0.960, p <0.001) for the cutoff value of 1,279.52 with a sensitivity of 87.2%, specificity of 86.7%, PPV 90.4%, NPV 82.5%, +LR 6.5, and -LR 0.1. The area under curve for VAS scores >= 6 was 96.2% (95% CI 0.930-0.980, p <0.001) for the cutoff value 2,227.71, with a sensitivity of 90% and a specificity of 91.1%. In addition, a significant positive correlation between XBP-1 levels and endometrioma volume and VAS score was observed (r=0.51; r =0.79; r =0.65, respectively; p <0.001). CONCLUSION: XBP-1 levels in the study group were significantly higher than those of the control group. In addition, significantly higher levels of XBP-1 in patients with VAS scores of >= 6 have been reported.