Finding Out How Estrogen Affects Body Fluid Regulation

Nina S. Stachenfeld, Ph.D.,Assistant Professor of Epidemiology and Public Health

Improper body fluid balance can lead to debilitating illnesses (including certain cardiovascular diseases), surgical complications, and problems with body temperature regulation. Vulnerability to these diseases, complications and conditions increases dramatically in women, as does changes in body fluid regulation, when radical shifts in sex hormones occur with menopause. This suggests that female sex hormones play a role in the interaction of body fluid regulation and disease vulnerability. Dr. Stachenfeld examined the actions of estrogen and progesterone on the systems that regulate body fluid balance.  This study was directed at understanding body fluid regulation as it relates to prevention and/or treatment of acute conditions and chronic diseases affecting women.

Highlighted Study Findings

This study was designed to characterize the actions of estrogen and progesterone on the systems that regulate body fluid balance and affect disease vulnerability. Because estrogen and progesterone have opposing effects on water regulation, and increase concurrently, albeit cyclically, in women of reproductive age, it has been difficult to study the individual actions of these hormones. In this investigation, the natural production of estrogen and progesterone in young women was prevented using an agent that suppresses ovarian function. Each hormone was then added back either as estrogen alone or estrogen plus progesterone to determine how these hormones alter body fluid distribution. The findings support a role for estrogen in the maintenance of body fluids by adjusting vascular functioning. The findings further indicate that high plasma progesterone levels reverse the protective effects of estrogen on plasma volume. Understanding the role of estrogen and progesterone on body fluid regulation is necessary in strategies for decreasing surgical complications due to fluid imbalance. In addition to improving our understanding of the role of sex hormones on body fluid regulation, this study demonstrated the influence of fluid dynamics on responses to temperature challenges and facilitated in the development of new strategies to help women avoid heat exhaustion or heat stroke.