Hormonal Changes During Menopause and the Impact on Fluid Regulation

Abstract

Reproductive surgeries leave women more susceptible to postoperative hypervolemic hyponatremia because during this period women can retain water at an accelerated pace and much faster than they do sodium. This review proposes that estrogen and progestogen exposure play an important role in the increased risk of hyponatremia in menopausal women. Estrogen and progesterone exposure have important effects on both body fluid regulation and cardiovascular function and both of these reproductive hormones impact blood pressure responses to sodium loads. This article provides information on the effects of female reproductive hormones and hormone therapy (HT) on fluid regulation and cardiovascular function during menopause. Thirst-and fluid-regulating hormones respond to both osmotic and volume stimuli. Aging women maintain thirst sensitivity to osmotic stimuli but lose some thirst sensitivity to changes in central body fluid volume. Thus, older adults are more at risk of dehydration because they may replenish fluids at a slower rate. Estrogen therapy increases osmotic sensitivity for mechanisms to retain body water so may help menopausal women control body fluids and avoid dehydration. Some progestogens can mitigate estradiol effects on water and sodium retention through competition with aldosterone for the mineralocorticoid receptor and attenuating aldosterone-mediated sodium retention in the distal tubule. However, some progestogens can increase cardiovascular risks. Appropriate balance of these hormones within HT is important to avoid the negative consequences of body fluid and sodium retention, including edema and hypertension.Keywords hormone therapy, estrogen, progesterone, body fluid regulation, arginine vasopressin Reproductive surgeries leave women more susceptible to postoperative hypervolemic hyponatremia because women retain water at a faster rate than sodium during this period, 1-5 especially after reproductive surgeries. 4,7 Indeed, women are at high risk of postoperative hyponatremia even after relatively low-risk surgeries such as operative hysteroscopy. In such surgeries, glycine solution (lacking electrolytes) is used as a distension medium and can cause intravascular volume retention, increasing the risk of hyponatremia, cerebral and/or pulmonary edema, psychological disturbances, and even death. 4,[8][9] A combination of anesthesia, nausea, and the postsurgical experience tends to increase arginine vasopressin (AVP). This hormone, the primary hormone involved in free water retention, is also associated with altered astroglia volume regulation in both pre-and postmenopausal (PM) women. 3,5,10,11 Studies in animals support an important role for estradiol in increasing astroglia volume in women with hyponatremia, suggesting a role for female reproductive hormones in the dire consequences that can be associated with postoperative hyponatremia in both young and PM women. 6,12 Hormones During MenopauseThe stages of the menopause transition are classified by changes in menstrual bleeding, concomitant...

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