Estrogen is a steroid hormone that is synthesized in the body and secreted into the bloodstream, where it circulates throughout the body, affecting a number of tissues and organs. Estrogen is normally synthesized in the ovaries in females, and to a lesser extent the testes in men. Insufficient estrogen production leads to low estrogen levels, which lead to a number of side effects.
Hypogonadism
Hypogonadism is a disease that can occur before or after puberty and leads to low estrogen levels in females, or low testosterone levels in males. Girls with hypogonadism do not develop the normal symptoms of puberty, since their bodies do not produce enough estrogen. Normally, estrogen released during puberty would stimulate breast cell growth to lead to breast development, so girls with hypogonadism do not develop breasts properly. Estrogen is also involved in the maturation of the uterine lining in preparation for ovulation, so girls with hypogonadism do not ovulate and menstruate normally. The long-term effects of hypogonadism may include infertility. Columbia University reports that hypogonadism can be treated by hormone-based therapies to increase estrogen levels in affected females.
Hypopituitarism
Low estrogen levels may also be caused by hypopituitarism, a disease caused by limited functioning of the pituitary gland. The pituitary gland is a structure in the brain that controls the release of several hormones, including estrogen. Hypopituitarism can result in partial or complete loss of the anterior lobe of the pituitary, according to the University of Maryland Medical Center. The symptoms of hypopituitarism depend on which hormones are affected, and the symptoms may develop gradually or suddenly, depending on the severity of the disease.
Hypopituitarism leads to low estrogen when the pituitary fails to release a hormone called luteinizing hormone, which stimulates the release of estrogen. Patients with a loss of luteinizing hormone, and therefore a loss of estrogen, experience absent menstruation, sexual dysfunction and a loss of secondary sex characteristics.
Anti-Cancer Drugs
In some cases, a loss of estrogen is caused by cancer medication. This is especially true of a class of drugs designed to treat breast cancer, called aromatase inhibitors. Estrogen promotes the growth of breast tissue by stimulating cell proliferation, and estrogen also promotes the proliferation of breast cancer cells to contribute to cancer development. Aromatase inhibitors are frequently prescribed to treat estrogen-sensitive breast cancers, and they function to lower levels of estrogen to slow tumor growth.
Aromatase inhibitors work by preventing the synthesis of estrogen. Estrogen is made by modifying existing chemicals in the cell, a process which is carried out by proteins. Aromatase inhibitors stop the function of these proteins, halting estrogen production, and leading to low estrogen levels. Breast cancer patients taking aromatase inhibitors may experience side effects related to low levels of estrogen.
