Clonidine raises the sweating threshold in symptomatic but not in asymptomatic postmenopausal women

Objective: To determine the effects of clonidine, which reduces central sym pathetic activation, on the sweating threshold in postmenopausal women with and without hot flashes. Design: Laboratory physiologic study. Setting: University medical center. Patient(s): 12 healthy postmenopausal women reporting frequent hot hashes a nd 7 reporting none. Intervention(s): In two separate sessions, participants received a blind in travenous injection of clonidine HCl (2 mu g/kg of body weight) or placebo, followed by body heating. Main Outcome Measure(s): Core body temperature, mean skin temperature, swea t rate, sternal skin conductance level, and blood pressure. Result(s): Symptomatic women had significantly lower core body temperature sweating thresholds than asymptomatic women after receiving placebo. Clonid ine significantly increased this threshold in symptomatic women but lowered it in asymptomatic women. Conclusion(s): These results support the hypothesis that elevated brain nor epinephrine levels reduce the swearing threshold in symptomatic women, ther eby contributing to the initiation of menopausal hot flashes. (Fertil Steri l(R) 2000:74:20-3. American Society for Reproductive Medicine).