Menstrual Problems

Menstruation is the periodic discharge of blood and mucosal tissue from the uterus, which occurs approximately monthly in nonpregnant women from the onset of puberty to menopause and is necessary for female reproduction. Menarche, or the first menstrual period, occurs during puberty and signals the onset of the reproductive years of a woman. On the other end of the spectrum, the beginning of menopause is when there have been no menstrual periods for 12 consecutive months and no other biological or physiological cause can be identified. Between these two end points, women would ideally have normal, [Page 457]regular menstrual cycles, or eumenorrhea, that range from 21 to 35 days in length.

Menstrual cycles are counted from the first day of menstrual bleeding because the onset of menstruation corresponds closely with the hormonal cycle. The menstrual cycle may be divided into several phases and the length of each phase varies from woman to woman and cycle to cycle. During the follicular phase, estrogen slowly builds up. Meanwhile, the follicle matures. Estrogen peaks right before ovulation, or the release of the egg from the ovary. The surge of luteinizing hormone (LH) triggers ovulation. The egg travels through the fallopian tube and may be fertilized by a sperm in the process. If the egg is not fertilized within a day of ovulation, it dies and is resorbed. During the luteal phase, the corpus luteum, or the remainder of the follicle postovulation, produces progesterone, causing the intrauterine lining to accumulate. Once the corpus luteum degenerates and progesterone levels decline, the uterine lining is shed, indicating the start of the menstrual cycle.

Menstrual problems are characterized by the irregularity of menstrual cycles, or the unpredictable variability of intervals, duration, or bleeding. With regard to irregularities in ovulation, oligoovulation is the term for infrequent or irregular ovulation, defined as cycles of more than 36 days or fewer than 8 cycles a year. Anovulation is the absence of ovulation when it would be normally expected, such as in a postmenarchal, premenopausal woman. Patients with anovulation usually present with the irregularity of menstrual periods. Additionally, anovulation can also cause cessation of periods, also called secondary amenorrhea, or excessive bleeding, as characterized by dysfunctional uterine bleeding.

In terms of menstrual cycles, polymenorrhea refers to cycles with intervals of 21 days or less. Another condition is oligomenorrhea, defined as infrequent or light menstrual cycles with more than 35 days. Occurring in approximately half of patients with bulimia nervosa, the mechanism of oligomenorrhea appears to be related to hypothalamic-pituitary function.

Similarly, amenorrhea is a diagnostic criterion for anorexia nervosa. Amenorrhea is the absence of a menstrual period in a woman of reproductive age. Physiologic states of amenorrhea are seen during pregnancy and lactation, or breastfeeding.

In patients with anorexia, the exact mechanism of amenorrhea has yet to be elucidated. Nonetheless, severe caloric restriction suppresses the hypothalamic–pituitary axis, possibly mediated by cortisol, leptin, growth hormone, and insulin-like growth factor I, resulting in the suppression of the pituitary production of LH and FSH. Abnormally low levels of LH and FSH cause low levels of circulating estrogen, thereby blocking ovulation.

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