ObjectiveTo assess the association of hot flushes during postmenopause with oxidative stress and to determine whether hormone replacement therapy (HRT) affects the plasma redox status of postmenopausal women.MethodsWe conducted a prospective clinical study of 49 postmenopausal women who have (n= 29) or do not have (n= 20) hot flushes. Twelve of the postmenopausal women with hot flushes and six without were treated with HRT (estradiol patches and medroxyprogesterone acetate) for 4 months. Plasma level of estradiol, total antioxidant status, reduced sulfhydryl groups, lipoperoxides, total cholesterol, and triglycerides were measured at 4-month intervals in both groups, before and after treatment.ResultsPostmenopausal women who have hot flushes, had lower total basal antioxidant status in plasma (.9 ± .01 compared with 1.14 ± .01 mmol/L), lower concentration of reduced sulfhydryl groups (145 ± 4 compared with 200 ± 3 μmol/L), and higher concentration of lipoperoxides (2.88 ± .04 compared with 2.61 ± .04 μmol/L) than women without hot flushes. After HRT, total antioxidant status and reduced sulfhydryl groups increased, and lipoperoxides decreased similarly in both groups. Hormone replacement therapy decreased the frequency of hot flushes per day from 11.2 ± 0.8 to 1.4 ± 0.3.ConclusionHot flushes in postmenopausal women were associated with the oxidative process. Hormone replacement therapy decreases oxidative stress and the number of episodes of hot flushes. Because oxidative stress is associated with a high risk for cardiovascular diseases, HRT might protect women with hot flushes.