From Encyclopedia of Sex and Sexuality
One of the major female sex hormones. It is mainly converted from androgens in the ovaries and, to a lesser degree, in the adipose tissue. Estrogen is linked to other hormones in the body that control the level in the blood at various times. Estrogen is especially important in the menstrual cycle, during adolescence, and in pregnancy.
In the brain, the hypothalamus sends a message to the pituitary gland which then releases FSH (follicle stimulating hormone) and LH (leutinizing hormone), influencing the ova-containing follicles in the ovary. As a consequence, there is a proliferation of cells that stimulates the synthesis of estrogen. The increase of estrogen in the blood triggers the release of LH, causing a rupture of the follicle and releasing the mature egg. The ruptured follicle becomes the corpus leuteum, which responds to regression of LH by a decline in hormone production and endometrial shedding (menstruation).
Estrogen has other functions in the body besides menstruation. It is part of a coordinated group of hormones responsible for development and maturation of the breasts during puberty. Other changes that are due to estrogen are thickening of the labia minora, color change of the vaginal mucosa from bright red to pink, and the presence of mucoid vaginal secretions.
In the pregnant woman estrogen is part of a group of hormones responsible for breast tissue growth. Throughout life estrogen plays an important role in the balance of calcium in the bones. This becomes more noticeable as estrogen levels fall and bones become calcium deficient (osteoporosis).
As the woman matures and reaches menopause, many changes occur as a result of the reduction in estrogen. The most visible event is the cessation of menstruation. Other hormone–deficiency-related symptoms are genito-urinary atrophy, vasomotor instability (see hot flashes), and osteoporosis (loss of calcium from bones). Other probable hormone-related symptoms include atherosclerotic cardiovascular disease and psychosocial symptoms of insomnia, fatigue, and possibly depression.
Synthetic estrogen replacement is used to alleviate signs and symptoms of menopause. It has been found most useful for prevention or lessening of osteoporosis and for prevention of cardiovascular disease in women with a strong family history of this disease. Once the decision has been made to prescribe estrogen replacement therapy, the physician must determine which estrogen to use and the dosage, route of administration, and means of monitoring the therapy for each woman.
All patients receiving hormone replacement therapy should have an annual follow-up, including nutritional information, breast and pelvic examination, a Pap smear, and fecal occult blood. There is also a need for mammography and blood lipid screening (see also Amenorrhea).