By Susan Brinkmann, OCDS
Women who want to prolong childbearing into their later years – but who worry about the clicking of their biological clock – may soon be able to pinpoint the onset of menopause within one year.
Researchers at the University of Michigan have discovered new information about hormonal biomarkers that can address the beginning of the menopause transition.
“In the end, this information can change the way we do business,” said MaryFran Sowers, professor in the University of Michigan School of Public Health Department of Epidemiology. “The information provides a roadmap as to how fast women are progressing through the different elements of their reproductive life.”
Sowers’ team examined the naturally occurring changes in three different biomarkers over the reproductive life of more than 600 women: follicle-stimulating hormone (FSH), anti-Mullerian hormone (AMH) and inhibin B.
Researchers found that the biomarker AMH declined to a very low or non-measurable level five years prior to the final menstrual period. This decline pinpoints a critical juncture in which a woman probably has so few follicles (eggs) that her fertility becomes increasingly questionable, Sowers said. They found that the changes in AMH and inhibin B concentrations were predictive of the time to menopause.
They were also able to identify different reproductive stages by measuring the rates of change in FSH. Based on a woman’s age and the level of FSH in the blood, researchers were able to describe four different stages that occur in women from their late reproductive period to the time of their final menstrual period.
While clinicians have the ability to measure these hormones now, they haven’t had the kind of information about AMH, inhibin B or FSH collected on a large group of women over time to know how to relate levels or changes in the levels to fertility or to a menopause endpoint.
“People really want information about how long do I have and when will I have my final menstrual period,” Sowers said. “Now we are beginning to say, ‘If you have a specific FSH level combined with your age, this is the likelihood that you are in this reproductive stage.’
“We finally have numbers from enough women evaluated over a long time period to describe the reproductive aging process. It begins to give women and clinicians an expanded way to look at menses and endocrine events in terms of reproductive progression.”
Sowers said additional study results have been submitted to describe the amount of bone loss that occurs at the different FSH stages. Thus, if women and clinicians know where women are in the various reproductive stages, it will further their understanding of the likely health implications associated with each stage.
The research team also includes: Huiyong Zheng, Daniel McConnell, Bin Nan, Sioban Harlow, all of the University of Michigan School of Public Health, and John F. Randolph Jr. of the University of Michigan Department of Obstetrics and Gynecology.
The studies are available online at the Journal of Clinical Endocrinology and Metabolism.
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