Changes in nocturnal melatonin secretion in perimenopausal women: Correlation with endogenous estrogen concentrations

Although age-related decrease in melatonin secretion in humans and animals is well documented, there is a paucity of data on the precise changes in me latonin secretion that occur during the perimenopausal period. The present study was designed to measure changes in nocturnal melatonin and to charact erize the role played by estrogen in controlling nocturnal melatonin secret ion in perimenopausal women. Nocturnal serum melatonin concentrations were determined every 2 hr in 46 premenopausal women, 44 postmenopausal women, a nd 11 premenopausal women with uterine leiomyoma scheduled for hysterectomy and bilateral salpingo-oophorectomy. Nocturnal serum melatonin secretion i n premenopausal women declined moderately from 17 to 45 years of age, and i ncreased during the period from 46 to 50 years of age. Among postmenopausal women, a steep, age-related decline in nocturnal melatonin secretion was f ound for up to 15 years postmenopause, followed by an extremely gradual dec line thereafter. A significant negative correlation was observed between th e peak serum melatonin concentration and the serum 17 beta-estradiol concen tration in premenopausal women aged 40-50 years (r = -0.661, P < 0.0005). D aily oral administration of conjugated estrogen (0.625 mg) to postmenopausa l women suppressed nocturnal melatonin secretion (P < 0.005). A low estroge n state, induced by oophorectomy of premenopausal women with uterine leiomy oma led to an increase in nocturnal melatonin secretion (P < 0.0001). Our f indings suggest that transient elevated nocturnal melatonin secretion durin g menopause may be related to the existence of a low estrogen environment. The age-related decrease in melatonin secretion observed in other condition s is most likely attributable to other age-related factors.