Amenorrhea, more commonly known as Menstrual Irregularities, means the absence of periods. The term is generally further classified as primary amenorrhea, meaning that an individual has not started menstrual cycles by the age of 16, and secondary amenorrhea, where an individual who previously had periods has not had a menstrual cycle for more than three to six months.
The causes of amenorrhea can be diverse. The brain (including the hypothalamus and pituitary gland), the ovaries, and the uterus all play a role in orchestrating the hormonal events necessary to prepare for pregnancy, and, if a woman does not become pregnant, to have a period every month. Problems can arise at every level.
Pregnancy is the most common cause of amenorrhea. In women who have never had a period, developmental problems of the uterus or the vagina may be the cause. Frequently, ovarian conditions such as polycystic ovarian syndrome can cause amenorrhea. Less frequently, ovarian failure (premature menopause) is the reason.
Finally, problems at the level of the hypothalamus and pituitary gland can arise. Hypothalamic amenorrhea occurs when the hypothalamus fails to release a hormone called GnRH (gonadotropin releasing hormone) in a normal fashion. This is often related to having a low body weight, increased stress levels, or strenuous exercise. The pituitary gland within the brain also releases hormones (follicle stimulating hormone or FSH, and luteinizing hormone or LH) in a cyclic fashion as directed by GnRH release from the hypothalamus that are involved in menstruation.
Problems with other hormones also housed in the pituitary gland, such as thyroid stimulating hormone (TSH) or prolactin can cause menstrual irregularities.
To fully evaluate amenorrhea, a physician will perform a complete medical history and physical exam. Next, blood work is generally obtained to assess for pregnancy, and to check the status of the thyroid and prolactin levels. Sometimes, a short course of a medication called provera will be given to see if a period can be induced, which can indirectly test to see if the ovaries are producing estrogen. Finally, if an ovarian or hypothalamic / pituitary cause is suspected, FSH and LH levels will be checked. If there is concern for abnormalities with the pituitary or hypothalamus, often an MRI will be obtained to visualize this area.
Treatment for amenorrhea will be dictated by the cause, and the goal of therapy is to correct the underlying abnormality.