Effects of symptomatic status and the menstrual cycle on hot flash-related thermoregulatory parameters.

Objective: To compare core body temperature variation, sweating thresholds, and sweat rate in symptomatic and asymptomatic postmenopausal women and in eumenorrheic women in the follicular and luteal phases.

Design: Twelve symptomatic and 10 asymptomatic postmenopausal women and 12 eumenorrheic women were recorded in a temperature- and humidity-controlled laboratory during thermoneutral and warm conditions. Core body temperature variation was measured with an ingested radiotelemetry pill, basal body temperature with a rectal thermistor, skin temperature with four skin surface thermistors, and sweat rate with a capacitance hygrometer.

Results: Symptomatic women had significantly lower sweating thresholds and higher maximum sweat rates compared with all other women. These results could not be explained by differences in estrogen, progesterone, or body mass index.

Conclusions: Postmenopausal women with hot flashes are uniquely characterized by low sweating thresholds and high sweat rates, relative to asymptomatic and eumenorrheic women.