ESTROGEN RAISES THE SWEATING THRESHOLD IN POSTMENOPAUSAL WOMEN WITH HOT FLASHES
R.R. Freedman and C.M. Blacker,
Department of Psychiatry and Ob/Gyn, Wayne State University, Detroit, Michigan.
Hot flashes (HFs) are the most common symptom of menopause and consist of profuse
sweating, peripheral vasodilation, and sensations of intense heat. Recent research has shown
that HFs are triggered by small fluctuations in Tc acting within a reduced thermoneutral zone.
Although estrogen ameliorates HFs in most symptomatic women, its mechanism of action is
not known. Here we sought to determine if estrogen reduces Tc fluctuations and/or raises the
sweating threshold in postmenopausal women with frequent HFs. Twenty women were
randomly assigned to receive 17β-estradiol (1mg/day, p.o.) or placebo for 90 days. Before
treatment they had Tc (rectal) and Tsk (4 weighted sites) recorded in a 26°C, 50% RH room for
3 hours. Data were sampled every 15 sec by computer. Tc fluctuations were estimated by
computing the standard deviation (SD) for each subject's 3 hr recording. On a separate day the
Tc and Tsk thresholds for sternal sweating (capacitance hygrometry) were measured using 42°C
circulating water pads on the legs and torso. HFs were recorded for 2 weeks in diaries. After
treatment all procedures were repeated. Data were analyzed with 2-way repeated measures
ANOVAs and are shown in the table.
|
| Estrogen | Placebo
|
|
Tc | Pre | 37.9°C ± .2 | 37.9°C ± .2
|
|
(mean ± SD) | Post | 38.0°C ± .3 | 37.9°C ± .2
|
| |
|
Tsk | Pre | 34.0°C ± .4 | 34.0°C ± .5
|
|
(mean ± SD) | Post | 34.1°C ± .5 | 34.3°C ± .6
|
| |
|
Tc Swt.Th. | Pre | 37.9°C ± .3 | 38.0°C ± .2
|
|
(mean ± SD) | Post | 38.1°C ± .2* | 37.8°C ± .4
|
| |
|
Tsk Swt.Th. | Pre | 36.2°C ± 1.0 | 35.8°C ± .7
|
|
(mean ± SD) | Post | 35.9°C ± .4 | 36.2°C ± .8
|
| |
|
HFs/day | Pre | 7.9 ± 2.6 | 8.3 ± 5.4
|
|
(mean ± SD) | Post | 2.3 ± 1.9** | 5.7 ± 3.3
|
|
* p < .05 Pre vs. Post
|
|
**p <.001 Pre vs. Post
|
Mean Tc and Tsk did not significantly change in either group nor did the SD of Tc (estimate of
Tc fluctuations). Estrogen significantly raised the Tc sweating threshold and reduced HF
frequency in the treated group but not the placebo group. We conclude that estrogen therapy
ameliorates HFs by raising the Tc sweating threshold, but does not affect Tc fluctuations.
Supported by NIH Merit Award, R37-AGg05233}
aa2613@wayne.edu
