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This comprehensive guide explores menopause as a natural event in women, delving into the hormonal changes, ovarian follicle numbers, and endocrine features during different phases of menopausal transition. Learn about the relationships between FSH, inhibin, and androgens in perimenopausal and postmenopausal women. International research findings from NIH provide insights into women's health during menopause.
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Menopause:a natural event Henry Burger
Mean age 51 years 1 yearlater Climacteric Menopausal transition Perimenopause Postmenopause Final menstrual period (FMP) Menopause Relationships between different time periods surrounding the menopause International Position Paper: Women’s Health and Menopause, NIH (2002)
Ovarian follicle numbers with age Women in Block's study 100000 B Women from the present study with regular menses B 10000 B B J 1000 Postmenopausal women F F B Primordial follicles/ovary F 100 Perimenopausal women F F 10 F F 1 0 0 10 20 30 40 50 60 Age (years) Richardson et al.JCEM 1987
Hypothalamo-pituitary ovarian axis Hypothalamus Feedback hormones GnRH Pituitary Steroids Gonadotropins: - LH, FSH Inhibin Ovary
Relationships betweenFSH and inhibin B 4.5 < 40 years of age > 40 years of age 4.0 3.5 3.0 Log (FSH) 2.5 2.0 1.5 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Log (inhibin B) Burger HG et al.Climacteric 2000
Geometric mean annual hormone levels relative to date of final menses 300 120 250 100 200 80 150 60 FSH (IU/l) Estradiol (pmol/l) 100 40 50 20 0 0 -4 -3 -2 -1 0 1 2 3 4 5 60 60 50 50 40 40 30 30 Inhibin B (ng/l) Inhibin A (ng/l) 20 20 * (InhB) (InhA) 62% 57% 80% 65% 10 10 41% 36% 80% 80% 78% 78% 94% 94% 71% 43% 0 0 -4 -3 -2 -1 0 1 2 3 4 5 Years around menopause * Percent of samples with undetectable inhibin Burger HG et al. JCEM 1999
Androgensin the menopausal transition • In normal women, there is a 50% decrease in circulating concentrations of testosterone and dehydroepiandrosterone sulfate (DHEAS) from age 20 to age 451,2 • There is little if any decline in testosterone during the transition2,3 • DHEAS levels continue to fall with age, with no specific association with the transition • The medical ‘myth’ that menopause is associated with an acute drop in androgens does not appear to be tenable any longer 1Zumoff 1995, 2Davison 2005; 3Burger 2000
Other endocrine features • Loss of LH response to an estradiol challenge in the perimenopause1,2 • Predominant circulating estrogen in reproductive life is estradiol, secreted by the ovary; postmenopausally it is estrone, produced by peripheral androgen aromatization3 • Anti-Müllerian hormone (also called Müllerian inhibiting substance), a member of the TGF super family and a product of preantral and small antral follicles, is under investigation as a marker for the size of the ovarian follicle pool4 and a promising predictor for the occurrence of the transition5 1Van Look 1977; 2Weiss 2004; 3Maroulis 1976; 4Visser 2006; 5van Rooij 2004