1. Menopause: a natural event Henry Burger

2. Definitions (1) Menopause: The permanent cessation of menstruation resulting from loss of ovarian follicular activity. Recognized to have occurred after 12 consecutive months of amenorrhea. Often termed final menstrual period (FMP). There is no independent biological marker Perimenopause: The time immediately prior to the menopause (when the endocrinological, biological and clinical features of approaching menopause commence) and the first year after menopause

3. Definitions (2) Menopausal transition: The time before FMP when variability in the menstrual cycle is usually increased. It may be subdivided into: –early transition: ≥ 7 days persistent difference in cycle lengths from previous normal range –late transition: ≥ 60 days amenorrhea observed on at least one occasion Climacteric: The period marking the transition from the reproductive to the non-reproductive phase

4. Definitions (3) Premenopause: The entire reproductive period up to FMP Postmenopause: The phase dating from FMP, whether spontaneous or induced. May be subdivided into: –early postmenopause, first 5 years after FMP and –late postmenopause, more than 5 years after FMP

5. Relationships between different time periods surrounding the menopause International Position Paper: Women’s Health and Menopause, NIH (2002) Final menstrual period (FMP) Menopause Postmenopause Perimenopause Menopausal transition Climacteric Mean age 51 years 1 year later

6. Determinants of age of menopause Median age 45–55 years world-wide, 50–52 years in white women from industrialized countries Premature menopause conventionally defined as FMP occurring < 40 years, may have several causes Factors involved in earlier age of menopause: –oophorectomy, e.g. for endometriosis, cancer –chemotherapy, e.g. cyclophosphamide –ovarian irradiation –hysterectomy (up to 4 years advancement) –familial and genetic factors (e.g. ER-α polymorphism, twinning) –cigarette smoking – by about 2 years Factors involved in later age of menopause: –possibly later age at menarche, oral contraceptive use, longer menstrual cycle length, and parity

7. The menopausal transition A process which takes about a decade Earliest signs include –shortening of the menstrual cycle by 2–3 days, detectable at about age 38–40 1,2 –infertility – with associated oocyte aging, increased incidence of luteal insufficiency and anovulation 3 abnormal basal temperature in 30–50% of cycles after age 40 4,5 Menopause is marked by exhaustion of the ovarian supply of oocytes 6,7, numbers declining steeply from age 37–38 1 Lenton 1984; 2 Klein 1996; 3 Treloar 1970; 4 Dòring 1963; 5 Vollmann 1977; 6 Baker 1963; 7 Richardson 1987

8. Women in Block's study Women from the present study with regular menses Postmenopausal women Perimenopausal women Richardson et al. JCEM 1987 Ovarian follicle numbers with age B B B B B J F F F F F F F Age (years) 1 10 100 1000 10000 100000 0 0102030405060 Primordial follicles/ovary

9. GnRH Inhibin Pituitary Gonadotropins: - LH, FSH Steroids Hypothalamus Feedback hormones Hypothalamo-pituitary ovarian axis Ovary

10. Groome et al. JCEM 1996 Hormone levels: normal menstrual cycle 80 60 40 20 0 50 40 30 20 10 0 40 30 20 10 0 15 10 5 0 1500 1000 500 0 200 150 100 50 0 -14-70714 Days relative to midcycle LH peak Inhibin A (pg/ml) Progesterone (nmol/l) LH (IU) Inhibin B (pg/ml) Estradiol (pmol/l) FSH (IU)

11. Endocrine overview of the transition Represents the period of change from regular menstrual cyclicity to the postmenopausal state of amenorrhea with elevated gonadotropins, low inhibins A and B, low estradiol and estrone and low anti-Müllerian hormone Earliest hormonal change is increase in FSH, most easily detected on cycle days 2–5, occurring in some women, mainly over age 40 (Sherman and Korenman 1976, followed by many others)

12. Increase in FSH Results from decreased inhibin feedback (first proposed by Sherman and Korenman 1976), specifically inhibin B secreted by the small antral follicles (Klein 1996, Burger 1999, many others) Occurs at a time when estradiol levels are maintained or increased – hence not a result of decreased estrogen feedback. The elevated FSH may lead to production of supra- physiological amounts of estradiol (Santoro 1996, Shideler 1989)

13. Log (inhibin B) 5.04.54.03.53.02.52.01.5 Log (FSH) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 Burger HG et al. Climacteric 2000 Relationships between FSH and inhibin B < 40 years of age > 40 years of age

14. Significance of FSH increase (1) A harbinger of menopause, although the increase may occur in some women many years before and without any change in menstrual cyclicity Augurs poorly for future fertility 1 Is a poor predictor of the age at menopause. The clinician cannot make any conclusions on the timing of an individual woman’s menopause based upon the presence or degree of FSH elevation 2 1 Pearlstone 1992; 2 Burger 1995

15. Significance of FSH increase (2) As long as the active follicular phase permitting the maturation of healthy follicles remains stable and the luteal phase normal, fertility is maintained Therefore contraception is still needed during the transition despite moderately elevated FSH levels An isolated elevation of FSH is not proof of the occurrence of menopause

16. Menstrual cyclicity Currently the best indicator of menopausal status Degree of irregularity highly variable between women, and regular cycles may recur after a period of irregularity, with temporary resolution of menopausal symptoms which may be associated with irregularity Variability includes short cycles, prolonged cycles with temporary ovarian inactivity, and skipped cycles with absence of ovulation Cycle length shortening is probably due to elevated FSH levels in the early follicular phase/late luteal phase Occurs when follicle numbers have fallen to around 100 per ovary 1 1 Richardson 1987

17. RegularPerimenopausalPostmenopausal 0.1 1 10 100 1000 10000 Primordial follicles/ovary Richardson et al. JCEM 1987 Ovarian follicle numbers in regularly cycling women and peri- and postmenopausal women (all > 45 years)

18. Characterization of the menopausal transition (1) Classic description was by Sherman and Korenman (1975) involving six women followed in detail up to and including final menstrual period Features include –monotropic rise in FSH secretion –continued folliculogenesis and evidence of ovulation up to the final menstrual period –periods of hypoestrogenemia concomitant with large FSH increases The loss of inhibin restraint was first hypothesized by these investigators

19. Characterization of the menopausal transition (2) Extensive and comprehensive longitudinal study of weekly urinary hormone excretion in 308 women aged over 40 years was reported by Metcalf and colleagues (summarized 1988) In 178 premenopausal women with regular cycles, cycle length was 26 days (95% CI 21–34) and 98% met criteria for ovulatory cycle FSH, LH compared in matching groups of 52 older women, median age 42, and 48 younger women, median age 33. FSH excretion was > 5 IU/24 h in 31.5% of the older group, 19.5% of the younger group A lesser, but significant rise in LH was also identified

20. Characterization of the menopausal transition (3) In 31 women, all of whom had experienced a sudden break in a previously regular succession of menstrual cycles, median cycle length was 29 days with range 18–260 days. Only 52% met the criteria used to identify an ovulatory cycle Ovulatory failure occurred in 80% of the 48 cycles > 40 days compared with 20% of shorter cycles Ovulatory cycles were seen at all stages during the menopausal transition; in four women, the last cycle before menopause was ovulatory There were marked variations in estrogen excretion with both persistently low and persistently raised levels The most characteristic feature was the sporadic appearance of persistently high levels of FSH and LH High gonadotropin levels were sometimes associated with high estrogen levels There was no evidence for a gradual decline in ovarian function during the transition

21. Metcalf, NZ Med J 1988 Phases associated with the end of reproductive life in normal women Premenopause Menopausal transition Perimenopause Postmenopause Ovarian senescence Menopause End of regular cycles Start of menstrual bleeding

22. Characterization of the early postmenopause Eight women were observed before and in the 6 months following last menstruation. The postmenopausal period could not be distinguished from the long anovulatory cycles of the menopausal transition 1 Elevated levels of estrogen excretion were observed after the menopause in five of the women The authors concluded that an endometrial rather than a hormonal event might determine the time at which menstruation stops during the menopausal transition 1 Metcalf, NZ Med J 1988

23. Characterization of the menopausal transition (4) Metcalf et al. (1981) classified cycles in perimenopausal women by changes in pregnanediol excretion (Classes I–IV) and in gonadotropin excretion (A–E and L) “The only generalization which can safely be made about menstrual cycles in perimenopausal women is that they are richly varied. There are long cycles and short cycles which are anovulatory and cycles resembling those in which ovulation is known to have occurred. Unpredictability is the norm, in marked contrast to the regular succession of ovulatory cycles observed in premenopausal women”

24. proportion resembling normal premenopausal cycles * Metcalf et al. J Endocrinol 1981 Classification of menstrual cycles on the basis of the premenstrual rise in pregnanediol excretion Menstrual cycles (%) Number of women having cycles of the stated class 2312618 100 80 60 40 20 0 10 5 0 Pregnanediol (µmol/24 h) IIIIIIIV * Class

25. FSH LH Classification of menstrual cycles into categories on the basis of gonadotropin excretion Metcalf et al. J Endocrinol 1981 10 5 0 10 5 0 Gonadotropin excretion (IU/24 h) ABCABC DELDEL

26. Other studies of the menopausal transition Longitudinal studies of transition have elucidated the underlying endocrinology (e.g. Burger 1995, 1998, 1999, 2000, 2005; Miro 2004, 2005; Landgren 2004; Gracia 2005) Mean FSH levels (based on annual single early cycle sampling) begin to rise ca. 2 years before FMP, increase most rapidly 10 months before, plateau 2 years after – values at FMP are 50% of this plateau (Burger 1999) Mean estradiol levels start to decrease 2 years before FMP, fall most rapidly around FMP, plateau 2 years after – values at FMP 50% of those before onset of decline (Burger 1999) The first endocrine marker seen at the onset of cycle irregularity is a fall in inhibin B (Burger 1998, Gracia 2005) Ovulatory cycles can be observed after the onset of the early and the late menopausal transition (Burger 2005)

27. Geometric mean annual hormone levels relative to date of final menses * Burger HG et al. JCEM 1999 0 10 20 30 40 50 60 -4-3-2012345 Years around menopause Inhibin A (ng/l) 0 10 20 30 40 50 60 Inhibin B (ng/l) 0 50 100 150 200 250 300 -4-3-2012345 Estradiol (pmol/l) 0 20 40 60 80 100 120 FSH (IU/l) (InhB) (InhA) 41% 36% 71% 43% 62% 57% 80% 65% 80% 78% 94% * Percent of samples with undetectable inhibin

28. 0 30 60 90 0 80 160 240 0 5 10 a a b b a a b b a a b b 0 20 40 60 1234 0 120 240 360 Category a b b b aa b b 1234 FSH (IU/l) RIA (IU/l) Inhibin A (ng/l) Estradiol (pmol/l) Inhibin B (ng/l) Burger et al. 1998 1 = Pre meno= STRAW -3 2 = Early peri= STRAW -2 3 = Late peri= STRAW -1 4 = Early post= STRAW +1 Reproductive hormone levels and menstrual cycle categories

29. Androgens in 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 45 1,2 There is little if any decline in testosterone during the transition 2,3 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 1 Zumoff 1995, 2 Davison 2005; 3 Burger 2000

30. Burger HG et al. JCEM 2000 Serum testosterone and menopausal transition 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 Time relative to FMP (years) Testosterone (nmol/l) -6-4-202468

31. Other endocrine features Loss of LH response to an estradiol challenge in the perimenopause 1,2 Predominant circulating estrogen in reproductive life is estradiol, secreted by the ovary; postmenopausally it is estrone, produced by peripheral androgen aromatization 3 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 pool 4 and a promising predictor for the occurrence of the transition 5 1 Van Look 1977; 2 Weiss 2004; 3 Maroulis 1976; 4 Visser 2006; 5 van Rooij 2004