Abstract
The significance of trace metal elements in the development of endometriosis has garnered increasing interest. We aimed to investigate the relationship between serum copper (Cu), zinc (Zn), iron (Fe), magnesium (Mg) levels, and the Cu/Zn ratio with the risk of endometriosis. This study involved 568 infertile patients diagnosed with endometriosis, compared to 819 infertile patients without endometriosis (Control group). Basic characteristics, hormonal parameters, and essential trace elements of the patients were measured and analyzed. The findings indicated a notable decrease in serum Zn levels in the endometriosis group compared to controls, alongside a significant increase in the Cu/Zn ratio (P < 0.001). Restricted cubic spline analysis (RCS) revealed a linear relationship between Zn levels and the Cu/Zn ratio with the risk of endometriosis. Moreover, Zn levels exhibited a negative correlation with endometriosis risk (P trend = 0.005), while the Cu/Zn ratio displayed a positive correlation with endometriosis risk, even after adjusting for age, body mass index (BMI), and baseline hormones (P trend < 0.001). Compared to the first quartile of Cu/Zn ratio after adjustment, the odds ratios (ORs) with 95% confidence intervals (CIs) for the second and fourth quartiles were 1.97 (1.37, 2.83) and 2.63 (1.80, 3.84), respectively. This study provided evidence of decreased serum Zn levels and increased Cu/Zn ratio being associated with an elevated risk of endometriosis among infertile patients.