Estrogen raises the sweating threshold in postmenopausal women with hot flashes

Objective: To determine if estrogen ameliorates hot flashes by raising the core body temperature sweating threshold, by reducing core body temperature fluctuations, and/or by reducing sympathetic activation (as measured by plasma 3-methoxy-4-hydroxyphenylglycol). Design: Laboratory physiological study. Setting: University medical center. Patient(s): Twenty-four healthy postmenopausal women reporting frequent hot flashes. Intervention(s): Participants were randomly assigned, in double-blind fashion, to receive 1 mg/d 17beta-estradiol orally or placebo for 90 days. Main Outcome Measure(s): Core body temperature, core body temperature fluctuations, mean skin temperature, sternal sweat rate, laboratory hot flash counts (sternal skin conductance), plasma 3-methoxy-4-hydroxyphenylglycol. Result(s): The E-2 group had significant increases in plasma E, (8 +/- 2 vs. 132 +/- 22 pg/mL) and core body temperature sweating threshold (37.98 +/- 0.09 vs. 38.14 +/- 0.09degreesC) and decreases in plasma FSH (58.8 +/- 8.9 vs. 40.1 +/- 7.6 mIU/mL) and hot flashes (1.4 +/- 0.5 vs. 0.6 +/- 0.6). These changes did not occur in the placebo group. There were no significant changes in any other measure. Conclusion(s): E, ameliorates hot flashes by raising the core body temperature sweating threshold, but does not affect core temperature fluctuations or plasma 3-methoxy-4-hydroxyphenylglycol. (Fertil Steril(R) 22002 77: 487-90. (C)2002 by American Society for Reproductive Medicine.).