Estrogen is a chemical that belongs to a family of compounds called steroid hormones. Estrogen is a female hormone produced by the ovaries that circulates in the blood to signal the tissues throughout the body. It signals the cells which contain a protein called the estrogen receptor, which binds to circulating estrogen and signals a biological change within the cell. Secretion of estrogen is tightly regulated and circulating estrogen levels normally fluctuate over the course of the menstrual cycle. A number of syndromes and conditions can lead to high levels of circulating estrogen in the blood.
Pregnancy
Pregnancy can lead to a sustained increase in estrogen levels. During the menstrual cycle, estrogen levels fluctuate and trigger changes within the breasts, leading to increased breast cell growth in preparation for pregnancy. Then estrogen levels fall again to begin the next menstrual cycle. If pregnancy occurs, estrogen levels remain high to allow for the development of tissues required to feed and support a baby.
During pregnancy, estrogen signals for an increase in breast cells, which leads to an enlargement of the breast, which is followed by maturation of milk-producing lobules to facilitate lactation. The uterus also secretes estrogen to sustain the pregnancy, according to the University of Illinois. Increased estrogen levels as a result of pregnancy are normal, and should not cause concern.
Adrenal Tumors
High estrogen levels that do not result because of a pregnancy may indicate a serious underlying disorder, such as an adrenal tumor. Adrenal cancer is a tumor affecting the adrenal glands, which are glands that sit on top of the kidneys. The adrenal gland secretes a number of hormones, including stress- or sex-related hormones, and precursors to estrogen. When tumors form on the adrenal glands, the tumor cells may release large amounts of estrogen precursors, leading to an unexplained increase in estrogen levels.
Patients with adrenal tumors may experience abdominal pain, as the tumor presses on healthy tissues within the abdomen. According to the University of Pennsylvania's website OcoLink:, patients may also experience a number of hormone-related symptoms, such as abnormal hair growth or hair loss, impotence or breast growth in men.
Ovarian Tumors
Sustained increased estrogen levels could also result from ovarian tumors. The ovaries are the major organs responsible for secreting estrogen during pregnancy and throughout the menstrual cycle, so the development of ovarian cancer may increase the number of estrogen-secreting cells to increase the levels of circulating estrogen in the blood.
A specific type of ovarian cancer, called a stromal tumor, commonly secretes estrogen, according to the University of Maryland Medical Center. These tumors develop from the connective tissue that supports the structure of the ovaries, and accounts for around six percent of ovarian cancer cases. If stromal tumors develop and become metastatic, they can become difficult to treat and control.
