RESUMEN
OBJECTIVE: There is currently little longitudinal data available on the serum hormonal characteristics of the menstrual cycles observed in women as they approach their final menstrual period (FMP) or menopause. We sought to determine whether the onset of irregular menses, marking the menopause transition, signifies the occurrence of anovulatory, potentially infertile cycles. DESIGN: We studied 12 subjects, initially aged 45 to 47 years, who provided daily menstrual diaries, and had blood samples collected annually, three times weekly for 4 consecutive weeks, over a period of 36 to 98 months until FMP, for measurements of serum follicle-stimulating hormone (FSH), luteinizing hormone, estradiol, and progesterone. The definition of entry into the early menopause transition was the occurrence of more than two cycles, in any consecutive sequence of 10, where cycle length was less than 23 or more than 35 days. Entry into the late transition was determined from the first observation of either 60-day or 90-day amenorrhea. Cycles were characterized endocrinologically as normal ovulatory, abnormal luteal phase, and anovulatory with evidence of ovarian follicular activity. RESULTS: The early transition had an average duration of 47 months from onset until FMP. Ten of the 12 subjects had one or more ovulatory cycles during the transition. Anovulatory cycles with ovarian activity were noted in 9 of the 12 subjects, only after entry into early and/or late transition. CONCLUSIONS: Ovulatory cycles occurred both before and after entry into the early and/or late menopause transition in subjects older than 45 years of age, whereas anovulatory cycles were observed only during the transition. The ovulatory cycles were generally associated with normal menses, whereas anovulatory cycles showed long duration and/or abnormal bleeding patterns. The occurrence of cycle irregularity is associated with an increasing frequency of anovulatory cycles, which herald the occurrence of FMP. No conclusion could be drawn regarding the appropriate definition of entry into the late transition. The definition adopted for entry into the early transition merits further validation.
Asunto(s)
Hormonas/sangre , Menopausia/fisiología , Ciclo Menstrual/metabolismo , Ovario/metabolismo , Anovulación/sangre , Anovulación/metabolismo , Estradiol/sangre , Femenino , Hormona Folículo Estimulante/sangre , Humanos , Estudios Longitudinales , Hormona Luteinizante/sangre , Ciclo Menstrual/sangre , Persona de Mediana Edad , Progesterona/sangreRESUMEN
To examine the hormonal characteristics of menstrual cycles in healthy women approaching menopause, serum hormone profiles were investigated annually in this longitudinal study of 13 healthy women between 4 and 9 yr before menopause and the year of the menopause. Serum FSH, LH, estradiol, progesterone, total inhibin, inhibins A and B, and prolactin were determined in blood samples collected annually three times weekly for 4 wk beginning with the onset of menses. Menstrual bleeding diaries covering this 4- to 9-yr period were also collected allowing the prospective identification of the final menstrual period. A change in serum hormone patterns was observed in cycles approaching menopause, exemplified by an increasing number of cycles of prolonged length with a prolonged follicular phase resulting in a failure to detect a luteal phase rise in serum progesterone within the 4-wk collection period. These prolonged cycles (designated B cycles based on a previous work) were analyzed separately and compared with the remaining ovulatory (D) cycles. No B cycles were identified in any women earlier than 27 cycles from menopause. The proportion of B cycles increased as menopause approached, reaching 62% in the last 10 cycles. The proportion of D cycles decreased accordingly. The B cycles during the initial 4-wk collection period were characterized by elevated FSH, LH, FSH/inhibin A and FSH/inhibin B ratios, and longer duration, although cycle length/subject was not significantly different presumably due to the small number of B cycles. The D cycles showed no changes in hormonal profiles over the 4- to 9-yr time period. These data indicate that there is a time-related change in the character of menstrual cycles as menopause approaches, with an increasing proportion of cycles observed with prolonged follicular phases that may either be delayed ovulatory cycles or anovulatory cycles. The increase in the proportion of B cycles with elevated early follicular phase FSH levels and low inhibin/FSH ratios toward menopause provides a basis for the apparent early increase in serum FSH and decrease in serum inhibins observed previously in studies of the menopause transition based on sampling confined to the follicular phase only. The data amplify and clarify current concepts of the endocrine basis of the menopause transition.