Menopause as risk factor for oxidative stress

Objective: The aim of this study was to determine the influence of menopause (hypoestrogenism) as a risk factor for oxidative stress. Methods: We carried out a cross-sectional study with 187 perimenopausal women from Mexico City, including 94 premenopausal (mean +/- SD age, 44.9 +/- 4.0 y; estrogen, 95.8 +/- 65.7 pg/mL; follicle-stimulating hormone, 13.6 +/- 16.9 mIU/mL) and 93 postmenopausal (mean T SD age, 52.5 +/- 3.3 y; estrogen, 12.8 +/- 6.8 pg/mL; follicle-stimulating hormone, 51.4 +/- 26.9 mIU/mL) women. We measured lipoperoxides using a thiobarbituric acid-reacting substance assay, erythrocyte superoxide dismutase and glutathione peroxidase activities, and the total antioxidant status with the Randox kit. An alternative cutoff value for lipoperoxide level of 0.320 mu mol/L or higher was defined on the basis of the 90th percentile of young healthy participants. All women answered the Menopause Rating Scale, the Athens Insomnia Scale, and a structured questionnaire about pro-oxidant factors, that is, smoking, consumption of caffeinated and alcoholic beverages, and physical activity. Finally, we measured weight and height and calculated body mass index. Results: The lipoperoxide levels were significantly higher in the postmenopausal group than in the premenopausal group (0.357 +/- 0.05 vs 0.331 +/- 0.05 mu mol/L, P = 0.001). Using logistic regression to control pro-oxidant variables, we found that menopause was the main risk factor for oxidative stress (odds ratio, 2.62; 95% CI, 1.35-5.11; P < 0.01). We also found a positive correlation between menopause rating score, insomnia score, and lipoperoxides, and this relationship was most evident in the postmenopausal group (menopause scale, r = 0.327 [P = 0.001]; insomnia scale, r = 0.209 [P < 0.05]). Conclusions: Our findings suggest that the depletion of estrogen in postmenopause could cause oxidative stress in addition to the known symptoms.