There are two types of amenorrhea, primary and secondary. Primary amenorrhea is delayed menarche (the first menstrual period) and is defined as any one of three conditions:
1.) absence of menarche by age 16 with otherwise normal pubertal development (development of breasts and/or pubic hair)
2.) absence of menarche by age 14 with delayed pubertal development
3.) absence of menarche two years after puberty is otherwise completed
Family history should be taken into consideration in any adolescent with primary amenorrhea. Mothers who started to menstruate late will often have daughters who also menstruate late.
Secondary amenorrhea is the absence of menstruation after menarche has taken place. Although it is not uncommon for menstrual periods to be irregular during early adolescence , periods usually become regular within 18 months after the first one. After that time, it is considered abnormal for an adolescent to miss three consecutive periods.
An adolescent with amenorrhea most likely does not have a serious underlying medical problem. Even so, all teenagers with amenorrhea should seek medical care, and an adolescent who has had sexual intercourse even once and then missed a period should assume she is pregnant until a reliable pregnancy test proves otherwise. It should be noted that spotting, or even bleeding, is not unusual during early pregnancy. In addition, it is possible for a girl to conceive before she has had even one period.
Other causes of amenorrhea
If pregnancy is ruled out as the cause of an adolescent's amenorrhea, a doctor will consider several other causes. After pregnancy, the most common reason for amenorrhea (both primary and secondary) is that the ovaries are not receiving appropriate messages from the hypothalamus and the pituitary gland. When this happens, the ovaries do not produce adequate amounts of hormones to trigger menstruation .
Less common causes of amenorrhea include pituitary tumor or a problem with the ovaries or uterus. In most cases, however, amenorrhea does not indicate a serious medical problem, and regular periods will resume without any treatment.
Emotional stress will sometimes prevent the brain from signaling the ovaries properly. It is not uncommon for a woman's period to be delayed when she is having problems with school, work, or relationships. A change in environment (the start of college, for example) can also cause a period to be late.
Physical stress is a common cause of amenorrhea. A girl who is too thin or has too little body fat may not begin to menstruate at the expected age. In girls who have started menstruating, insufficient body fat may cause the periods to stop. Athletes and other women who exercise strenuously sometimes experience amenorrhea even when their body weight and body fat levels are within normal ranges.
One way to determine whether a teenager's ovaries and uterus are functioning is a "progesterone challenge test." In this test, an amenorrheic teenager is given a dose of progesterone, either orally or as an injection. If her ovaries are making estrogen and her uterus is responding normally, she should start a menstrual period within a few days of the progesterone dose. This indicates that the ovaries and uterus are functioning normally, and the cause of the amenorrhea is probably in the brain.
Risks and treatment
The most serious risk associated with amenorrhea is osteoporosis (thinning of the bone) caused by low estrogen levels. Because osteoporosis can begin as early as adolescence, hormone replacement therapy is sometimes recommended for teenagers with chronic amenorrhea.
For Your Information
- Bell, Ruth, et al. Changing Bodies, Changing Lives . New York: Vintage, 1988.
Gale Encyclopedia of Childhood & Adolescence. Gale Research, 1998.