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.