Association between serum concentrations of nitric oxide and transition to menopause

Objective Menopausal status may increase cardiovascular disease ( CVD ) risk. Nitric oxide plays a role in the protection against CVD onset and progression but has not been studied around the time of menopause. We investigated associations between serum nitric‐oxide metabolite ( NO x) concentrations and menopausal status. Design Comparative case‐control cross‐sectional study. Setting Tehran Lipid and Glucose Study, university center. Sample Sub‐groups from a cohort of 2137 women, of whom 213 met enrollment criteria. Methods We studied four sub‐groups in a 1.2 ratio: (1) post‐menopausal women ( n  = 29) with natural amenorrhea for 13–24 months, (2) age‐ and BMI ‐matched controls ( n  = 58) with regular menstrual cycles; (3) peri‐menopausal women ( n  = 42) with natural amenorrhea for 1–12 months, and (4) age‐ and BMI ‐matched women as controls for the last group of women ( n  = 84). Main outcome measure Serum nitric oxide concentrations. Results Medians (inter‐quartile ranges) of NO x in post‐menopausal women and their controls were 31 (21.7–40.2) and 23.5 (17.2–31) μmol/L, respectively ( p  = 0.012). In peri‐menopausal women and their controls the medians (inter‐quartile ranges) were 28 μmol/L (18.5–50.5) and 25 (20–31.25) μmol/L, respectively ( p  = 0.035), but were not significantly different between peri‐ and postmenopausal women and were unchanged after adjustment for lipids. In a conditional fixed‐effect logistic regression model, the risk of “transition to menopause” and “menopause” rose respectively 2.44‐ and 2.27‐fold for a one‐score increase in the NO x standard deviation. Conclusion Menopausal status, by itself and not as a consequence of aging, is associated with increased serum nitric oxide concentrations. Identification of variables associated with menopausal cardiovascular consequences may be used to improve women's health after menopause.