Climacteric vasomotor symptoms do not imply autonomic dysfunction

Objective To study whether oestrogen replacement therapy has an effect on a utonomic haemodynamic control in postmenopausal women. Design A placebo-controlled, prospective, randomised, double-blind cross-ov er trial. Population Fourteen healthy postmenopausal women who had had a hysterectomy , of whom 12 were double-blind. Methods At the end of each treatment period we conducted autonomic nervous system tests: the Valsalva manoeuvre, the deep breathing test, study at res t and the active orthostatic test. Baroreflex sensitivity was evaluated non -invasively from the Valsalva manoeuvre. Heart rate variability was assesse d in time and frequency domains during supine rest and standing. Serum oest radiol was also measured and the previous two weeks' symptoms, were assesse d. Results Autonomic nervous function was mostly normal for age and unchanged by oestrogen. Vasomotor symptoms were not associated with autonomic dysfunc tion. Baroreflex sensitivity was 13.3 ms/mmHg (SD 7.4 ms/mmHg) with placebo and 10.5 ms/mmHg (SD 5.4 ms/mmHg) with oestrogen (P = 0.052). This was mos tly due to a fall in three of the highest indices. In the orthostatic test the 30 s blood pressure overshoot in two women exceeded the normal 90% conf idence interval upper limit, making the mean response strong, especially in the symptomatic group (n = 7). Oestrogen attenuated this overshoot. Conclusions Oestrogen did not have a consistent effect on the autonomic ner vous system. Oestrogen attenuated a highly sensitive baroreflex and a stron g 30 s blood pressure rise in the orthostatic test. This minor effect of oe strogen could be due to the fact that, in general, women with menopausal sy mptoms do not have impaired autonomic haemodynamic control. The effect of o estrogen in women with autonomic nervous system dysfunction remains to be s tudied.