- Clinical science
Estrogen is a female sex hormone that is produced in the ovaries and, to a lesser degree, in the adrenal glands and adipose tissues. It is essential for the development of primary and secondary sex characteristics, as well as function of the reproductive organs. Estrogen also plays a role in several other processes, including bone metabolism and liver function. While ovarian insufficiency, aromatase deficiency, and hyperprolactinemia result in pathologically low estrogen levels, a decrease in estrogen is a normal feature of menopause. Possible symptoms of estrogen deficiency include menopausal symptoms, vaginal and endometrial atrophy, and osteoporosis. Increased estrogen levels may also have adverse effects, including gynecomastia, thrombosis, and an increased risk of breast and endometrial cancer.
- Estrogen synthesis primarily takes place in the ovarian granulosa cells
- Estrogen is also produced in other aromatase-containing tissues:
- Types of estrogen: estradiol, estrone, estriol
Measurement of unconjugated estriol (uE3 or free estriol) is part of the prenatal screening for fetal anomalies (i.e., triple screen test and quad screen test). Decreased levels are associated with Down syndrome, Edward syndrome, molar pregnancy, and fetal demise.
- Uterus: endometrial proliferation
- Cervix: increased production of cervical mucus → facilitates passage of sperm, facilitates cervical dilation during labor
- Vagina: proliferation of epithelium
- Pubis: hair growth
- Breast: breast growth
- Bones: promotes bone formation by inhibiting bone resorption (induces osteoclast apoptosis)
- Blood vessels: protective effect against atherosclerosis
- Blood clotting: increased risk of thrombosis
- Kidneys: increased water and sodium retention → may contribute to edema
- Protein synthesis: slightly increased (anabolic effect)
- Liver: decreased bilirubin excretion
Adverse effects of estrogen can arise from high levels secondary to increased endogenous production or medication. :
- Weight gain (edema)
- Nausea and vomiting
- Liver toxicity
- Breast hypertrophy, gynecomastia (in men), galactorrhea
- Depressive moods
- Spider nevi, gynecomastia, and testicular atrophy in individuals with cirrhosis
- Increased cancer risk
High estrogen levels increase the risk of thrombosis!
- Definition: A condition of increased circulating estrogen.
- Men: gynecomastia, testicular atrophy, reduced libido, erectile dysfunction, infertility, decreased body hair (e.g., loss of chest hair, female pattern of pubic hair distribution)
- Women: menstrual irregularities, enlargement of the breast and uterus, infertility, and increased cancer risk (e.g., endometrial cancer)
- Both sexes: palmar erythema, spider telangiectasias
- Definition: A condition of decreased circulating estrogen.
- Clinical features