Estriol, also called estriol, is a female sex hormone that belongs to the estrogen group.
What is estriol?
Estriol is a hormone. It is one of the natural estrogens. However, compared to the other estrogens (estradiol and estrone), estriol shows only relatively weak estrogenic activity. The estrogenic effect is only about 1/10 as great as the effectiveness of estradiol. Estrogens such as estriol are the most important female sex hormones. They belong to the class of steroid hormones and are produced predominantly in the ovaries, corpus luteum and, to a certain extent, in the adrenal cortex. During pregnancy, production also occurs in the placenta. Men also have estriol. In them, it is produced in smaller quantities in the testes. All estrogens have the so-called estran (13β-methyl-gonan) as their basic structure. The German chemist Adolf Butenandt first succeeded in isolating estrogens and determining their structure in 1929.
Function, action, and roles
Estriol binds to receptors in the cell nucleus and stimulates cells to produce various proteins. This initiates and regulates numerous bodily processes. Estrogens are involved in controlling the female menstrual cycle. They ensure that the egg follicle in the ovaries matures. Likewise, estrogens influence the condition of the uterine lining. Estrogens cause the lining of the uterus to build up so that the egg can implant there after fertilization. Estriol also influences the growth of breast tissue. Estriol inhibits bone resorption by deactivating osteoclasts and at the same time increases the concentration of HDL cholesterol. HDL cholesterol has a positive effect on cardiovascular health. Estriol is known for its positive effect on mucous membranes. Estriol makes the mucous membranes in the urogenital tract, intestines and joints more resistant to bacteria, viruses and other microorganisms. Wound healing after injuries or operations can also be accelerated by estriol. Menopausal women are often given estriol by their doctor. Indications for the use of estriol are bacterial vaginal infections, osteoporosis, skin atrophies in the genital area, frequent vaginal infections, urinary tract infections and urinary incontinence. Estriol may also be helpful for dry vaginal mucosa, itching and burning in the intimate area, and abnormal vaginal discharge.
Formation, occurrence, properties, and optimal values
The majority of estrogens, and therefore the majority of estriol, is secreted during the so-called ovulation phase. The ovulation phase is the phase of ovulation. In general, estrogens are the dominant hormones in the first half of the cycle. The hormones are produced in the theca cells and in the granulosa cells. During pregnancy, estrogens are also produced in the placenta. The synthesis pathway of estriol takes its starting point in cholesterol. Via pregnenolone, a further conversion into 17-OH-pregnenolone or into progesterone takes place. Here the synthesis pathway splits. From 17-OH-pregnenolone, DHEA-S is formed, then DHEA and subsequently androstenedione or androstenediol. Estrone can be formed from androstenedione with the help of the aromatase enzyme. Estriol is only formed in the following synthesis step. Estradiol is initially formed from testosterone, also with the help of aromatase. Estriol can be formed from estradiol. The synthesis pathway via progesterone is somewhat faster. Here, androstenedione or testosterone is formed from progesterone via an intermediate stage. From this step on, the synthesis pathway is similar to the pathway via DHEA. The conversion of androstenedione and testosterone into estrogens takes place to a large extent in fatty tissue. The normal values in serum are between 20-40 pg/ml.
Diseases and disorders
While estriol levels increase rapidly during pregnancy, a deficiency of estriol is most apparent during menopause. The hormone synthesis pathway of estriol shows why estriol deficiency is particularly common in the endocrine system. Estriol ranks last in the synthesis pathway. If cofactors needed to convert the preceding hormones are missing, or if there is a hormone deficiency in general, estriol is always affected because it is the last and thus weakest link in the chain. Other causes of estriol deficiency are weaknesses of the ovary or adrenal glands. Burnout syndrome can also be associated with low hormone levels.An estriol deficiency can cause various symptoms. For example, an estriol deficiency often manifests itself in increased susceptibility to infections, recurrent bladder infections, joint problems, dizziness, tinnitus and digestive complaints. Other chronic mucosal problems such as dry eyes, unclear digestive problems, or dry vaginal mucous membranes may also indicate an estriol deficiency. An excessively high estriol level only plays a role in the context of estrogen dominance. Estrogen dominance is a disturbed relationship between the sex hormones estrogen and progesterone. Estrogen levels do not necessarily have to be elevated in estrogen dominance. Low levels of estriol and estradiol can also lead to estrogen dominance if progesterone is very low. The effects of estrogen dominance are very diverse. One well-known symptom complex that occurs with estrogen dominance is premenstrual syndrome (PMS). In this case, various physical and psychological complaints occur a few days before menstruation. Typical symptoms are water retention, hypersensitivity and even depression, pain and ravenous appetite. Menopausal symptoms can also be caused by estrogen dominance. Furthermore, estriol dominance can result in complaints such as headaches, insomnia, dizziness, concentration problems, endometriosis, infertility and fibroids. Other parts of the hormonal system are also affected. For example, thyroid dysfunction, blood sugar regulation disorders and adrenal gland disorders can occur as part of estrogen dominance. Typical symptoms also include cravings for sweets, increased abdominal fat and joint complaints.
