The controversial endocrinology of the menopausal transition.

Perimenopause: The Complex Endocrinology of the Menopausal Transition

“…The mean FP estradiol level of 225 pmol/liter from combined data in 415 perimenopausal women as shown in Table 1 is more striking because in young women FP estradiol levels are low and range from 50 -200 pmol/liter, with a mean of 175 Ϯ 57 pmol/liter in the combined premenopausal controls ( Table 1). The high perimenopausal FP levels published by Burger and colleagues (31) are, in fact, not different from cycle mean estradiol levels (obtained by quantitative combined FP and midluteal phase samples) from two cycles in each of 66 ovulatory women studied in this laboratory (86,101).…”

“…The average estradiol levels are higher than normal premenopausal FP phase levels for all except the last group (86). In addition to the higher mean estradiol levels, more than 10% of the individual values in every group exceeded the mean laboratory normal midcycle estradiol peak level of 750 pmol/liter (32, 33) (Fig.…”

“…Also, no primary menstrual cycle data are available, although the hormonal analysis is in five different groups based on reported menstrual cycle characteristics (i.e., Group I includes women who reported no change in cycle interval or flow in the last year, and Group V designates women reporting no period for 3 months but who had experienced flow within the last 12 months). Despite this menstrual cycle classification (whose validity has been questioned) (86), the Melbourne Women's Midlife Health Study, as now reported, does not allow integration of data on hormonal levels with perimenopausal flow characteristics, vasomotor, and other experiences of perimenopausal women.…”

“…In general, these papers do not comment on the high estrogen levels they document. This omission may occur because high estrogen levels were contrary to their anticipated results (86). Finally, perimenopausal women have a higher (by almost 50%) frequency of anovulation compared with women in their twenties and thirties (16).…”

“…The endocrinology of the perimenopause has not recently changed. Rather, the construct that menopause is a time of low estrogen production likely led to an inability of scientists and clinicians to see the (intermittently) high estrogen levels that were present (86).…”