Amenorrhea Health Article

Definition

Amenorrhea is the medical term for the absence of menstruation. There are two types of amenorrhea, primary and secondary. Primary amenorrhea refers to delayed menarche (the first menstrual period) and is defined as any one of three conditions:

• the absence of menarche by age 16 in a girl with otherwise normal pubertal development (development of breasts and/or pubic hair)
• the absence of menarche by age 14 combined with delayed pubertal development
• the absence of menarche two years after puberty is otherwise completed

Secondary amenorrhea is defined as the absence of menstruation after menarche has taken place. Although it is not uncommon for a girl's menstrual periods to be irregular during early adolescence, most girls' 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.

Description

Normal menstrual periods are the result of proper functioning and synchronization of the hypothalamus, pituitary gland, and ovaries. The hypothalamus is the part of the brain that controls body temperature, cellular metabolism, and such basic functions as appetite for food, the sleep/wake cycle, and reproduction. The hypothalamus also secretes hormones that regulate the pituitary gland. The pituitary gland in turn produces hormones that stimulate the ovaries to secrete two hormones known as estradiol and progesterone. These ovarian hormones encourage the growth of the endometrium, which is the tissue that lines the uterus. If pregnancy does not occur, the endometrium breaks down and the uterus sheds the extra tissue during the next menstrual period.

Amenorrhea can result from an interruption at any of several points in the normal cycle:

• The hypothalamus and pituitary may fail to produce enough hormone to stimulate the ovaries to produce their hormones.
• The ovaries may fail to produce enough estradiol to stimulate the growth of the endometrium.
• There may be structural abnormalities in the uterus, cervix, or vagina that prevent the shed tissue from leaving the body.

Demographics

Secondary amenorrhea is more common in females in North America than primary amenorrhea. One study estimates that about 5 percent of menstruating women have an episode of secondary amenorrhea each year.

The average age for the onset of the menses in girls in the United States and Canada is 12.77 years. There is no evidence as of the early 2000s that the incidence of either primary or secondary amenorrhea is related to race or ethnic background.

Causes

There are a number of possible causes of amenorrhea:

• Pregnancy: An adolescent with amenorrhea most likely does not have a serious underlying medical problem. 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.
• Disorders of the hypothalamus or the pituitary gland: These problems may be associated with brain tumors.
• Ovarian disorders: These disorders may include premature ovarian failure or may be the side effects of chemotherapy or radiation therapy for cancer. Premature ovarian failure accounts for about 10 percent of cases of secondary amenorrhea.
• Hyperandrogenism: The overproduction of male hormones (androgens) by the girl's body can interrupt menstruation. Male hormones are produced in small quantities by all women, but some individuals produce excessive amounts, leading to such conditions as polycystic ovarian syndrome (PCOS), hirsutism (excessive growth of body hair), or abnormalities of the external genitalia. PCOS in adolescents is often triggered by obesity.
• Genetic disorders: Some genetic disorders that affect the X chromosome, such as Turner's syndrome, prevent normal sexual maturation in girls.
• Psychiatric disorders: Depression, obsessive-compulsive disorder, eating disorders, and schizophrenia can all cause disturbances of the menstrual cycle.
• Abuse of alcohol or other drugs: Excessive alcohol intake can lead to malnutrition, while cocaine and opioids (narcotics) can affect the menstrual cycle directly.
• Immunodeficiency disorders or conditions.
• Emotional stress: This disturbance can interfere with the brain's hormonal signals to the ovaries. It is not uncommon for a girl's period to be delayed when she is having problems with school, work, or relationships. A change in environment (the first year of college or taking a new job, for example) can also cause a young woman's period to be late.
• Female athlete triad: Female athletes at the high school or college level are at increased risk for a triad of disorders: excessive dieting or disordered eating, amenorrhea, and loss of bone minerals leading to osteoporosis. The triad was first formally named in 1993 but had been known to doctors for decades before. Girls who are involved in sports that emphasize weight control or a slender body build (gymnastics, track and field, cheerleading) are at greater risk than those who play field hockey, basketball, softball, or other sports that emphasize strength.