Blood & Laboratory Values

Estriol – Function & Diseases


Estriol , also known as 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. Compared to the other estrogens ( estradiol and estrone ), however, estriol shows only a relatively weak estrogenic effectiveness. 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 mainly produced in the ovaries , in the corpus luteum and to a certain extent also in the adrenal cortex . During pregnancy, production also occurs in the placenta . Men also have estriol. In them, it is formed in smaller amounts in the testicles . All estrogens have the so-called estrane (13β-methylgonane) as their basic structure. The German chemist Adolf Butenandt was the first to isolate and determine the structure of estrogens in 1929.

Function, effect & tasks

Estriol binds to receptors in the cell nucleus and stimulates the cells to produce various proteins. This sets in motion and regulates numerous bodily processes. Estrogens are involved in controlling the female menstrual cycle. They ensure that the egg follicle in the ovaries matures. 

Estrogens also affect the condition of the uterine lining . Oestrogens build up the lining of the uterus so that the egg cell can nest there after fertilization. The growth of breast tissue is also influenced by estriol. Estriol inhibits bone breakdown 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 the mucous membranes.

Estriol makes the mucous membranes in the urogenital tract, in the intestines and in the joints more resistant to bacteria, viruses and other microorganisms. Estriol can also accelerate wound healing after injuries or operations. Menopausal women are often given estriol by their doctor. Indications for the use of estriol are bacterial vaginal inflammation, osteoporosis, skin atrophy in the genital area, frequent vaginal infections, urinary tract infections and urinary tract incontinence.

Estriol can also be helpful for dry vaginal mucosa, itching and burning in the intimate area and abnormal vaginal discharge.

Formation, Occurrence, Properties & Optimal Values

The majority of the estrogens and thus also the majority of the estriol is secreted in 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. Hormones are produced in the theca cells and in the granulosa cells .

During pregnancy, estrogens are also produced in the placenta. The estriol synthesis pathway starts with cholesterol . A further conversion into 17-OH-pregnenolone or into progesterone takes place via the pregnenolone . Here the synthesis path divides. DHEA-S is formed from 17-OH-pregnenolone, then DHEA and subsequently androstenedione or androstenediol. Estrone can be formed from androstenedione with the help of the enzyme aromatase. The estriol is only formed in the following synthesis step.

Estradiol is also initially produced from testosterone with the help of the aromatase. Estriol can be formed from estradiol. The synthesis route via progesterone is somewhat faster. Here, progesterone is produced via an intermediate stage androstenedione or testosterone. From this step onwards, the synthetic route is similar to the route via DHEA. The conversion of androstenedione and testosterone into estrogens takes place to a large extent in adipose tissue. The normal values ​​in the serum are between 20-40 pg/ml.

Diseases & Disorders

While estriol levels rise rapidly during pregnancy, a lack of estriol is particularly evident during the menopause . The estriol hormone synthesis pathway shows why an estriol deficiency in the hormone system is particularly common. Estriol is the last in the synthetic pathway. 

If cofactors, which are necessary for the conversion of the preceding hormones, are missing or if there is a general hormone deficiency, estriol is always affected, since it is the last and therefore weakest link in the chain. Other causes of a lack of estriol are weaknesses in the ovaries or weaknesses in the adrenal glands. Burnout syndrome can also be associated with low hormone levels.

A lack of estriol can cause various symptoms. Estriol deficiency often shows up in increased susceptibility to infections , recurring cystitis , joint problems, dizziness , tinnitus and digestive problems . Other chronic mucosal problems such as dry eyes, unclear digestive problems or dry vaginal mucous membranes can also indicate an estriol deficiency.

Too high an estriol level only plays a role in the context of estrogen dominance. Estrogen dominance is an imbalance between the sex hormones estrogen and progesterone. In the case of estrogen dominance, the estrogen level does not necessarily have to be elevated. Low estriol and estradiol levels can also lead to estrogen dominance when progesterone is very low. The effects of estrogen dominance are very diverse. A well-known symptom complex that occurs with estrogen dominance is premenstrual syndrome ( PMS ). A few days before menstruation , various physical and psychological complaints occur.

Typical are water retention , hypersensitivity up to depression , pain and ravenous hunger . Menopausal symptoms can also be caused by estrogen dominance. In addition, estriol dominance can result in symptoms such as headaches , insomnia , dizziness, difficulty concentrating , endometriosis , infertility and fibroids .

Other parts of the endocrine system are also affected. In the context of estrogen dominance, thyroid dysfunction , blood sugar regulation disorders and adrenal gland disorders can occur. Typical symptoms are also cravings for sweets, increased abdominal fat and joint problems.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.