Many people often mistakenly believe that estrogen and estradiol mean the same. The word “estrogen” is often used in the singular. Actually, the difference between them is that estrogens are a steroidal group, consisting of estriol, estradiol, estrone, and others. The common chemical structure unites them. Estradiol is considered the most potent hormone of the three; maybe, therefore, it is often called estrogen.
Some Historical & Scientific Facts
In 1923, the identifying of follicular hormones was made by the American scientists Edward Adelbert Doisy (1893–1986) and Edgar Allen (1892–1943). As reported by Brendan Van Iten (Embryo Project Encyclopedia, 2017), the researchers extracted estrogen from follicles of hogs. Three years after they received a crystalline form of one of them. This laid the foundation of the discovery and further examination of estrogens, one of the most crucial types of sex hormones.
The name of the hormone is derived from the Greek word. In transcription it sounds like “oistros”, meaning inspiration in translation. The suffix “-gen” gives it a complementary sense, namely generating or causing.
The human body is not a unique fount of the hormones’ synthesis; they are found in all vertebrates and some insects. Even certain plant species, in particular, sage and stevia, contain agents, called phytoestrogens (plant-derived xenoestrogen substances), featuring the structure and effect, similar to estrogens. These substances’ constitution provides an estrogenic and anti-estrogenic action. Nowadays, studies, conducted for revealing the influence of phytoestrogens on the organism, are proceeded. A typical example of the hormonal impact of the substance on mammals is the so-called “clover disease” detected in sheep and other pastoral representatives. Farmers have revealed that ewes, fed by mostly Trifolium subterraneum (subterranean trefoil) kind of the herbs, face infertility & other disorders of the reproductive system. They are triggered by isoflavone substances, providing a hormone-like influence on the sheep. Male sheep (jumbucks) grazing subterranean clover may face serious mortalities as reported by Rachel E. Cianciolo and F. Charles Mohr (2016).
Features of Estradiol
Estradiol without exaggeration can be called the basic estrogen in the females (however in the male organism it is also presented). It is produced mainly by the ovaries and adrenal glands (in a very small amount).
Its amount varies in different phases of the cycle. At the very beginning, the level is low, but before ovulation, its quantity gets bigger threefold, and on the cycle’s termination, if pregnancy doesn’t take place, it decreases again.
Numerous surveys prove that estradiol is involved in many female vital processes, in particular:
- Determining the proper blood cholesterol levels and promoting blood coagulation.
- Ensuring bone density.
- Regulating the vasculocardiac, nervous system.
- Maintaining a necessary water-salt balance.
- Affecting the intimate life and the normal functioning of the genitals.
- Promoting muscle enlargement (‘its the key hormone responsible for the growth of muscle mass in women instead of testosterone, therefore if a woman takes steroids such as testosterone cypionate, she develops masculinization, that is, masculine traits);
- Facilitating the follicle maturing, fertilization, fixation, and development of the embryo.
In general, estradiol provides over 400 functions for a woman. In postmenopause, when the follicles are no longer available, there is no organ to “manufacture” estradiol and its key source are lost. Ovarian estrogen synthesis begins to decrease 1 or 2 years before the climacteric. It reaches a stable nadir about 2 years after the last menstruation (Victor W. Henderson, 2008).
After this, various post-menopausal skin lesions, osteoporosis, muscle atrophy and their replacement with fat, and other negative consequences appear. To minimize such conditions, various estrogen pills, creams, etc. may be prescribed.
As stated by Michael Schulster, Aaron M Bernie, and Ranjith Ramasamy (2016), estradiol is also important for the male reproductive function. It is produced by Leydig, Sertoli and Germ cells in the testes and is responsible for testosterone modulation.
Estradiol vs Estrogen: the Difference
It’s a misapprehension that estrogen and estradiol are identical agents. They are not even synonymic. Estrogens are three basic hormones (not a single one). To date, approximately 30 kinds are described.
Perhaps, they share only one feature: with a lack of any of these hormones the adequate flow of pregnancy and the general female health will be in question. Therefore, the term “estrogens” is more accurately used to denote the whole class.
In most cases, test, aimed at revealing estrogen rate, implies the determination of estradiol alone. The only exception is the triple test, also named triple screen, conducted in the early childbearing phase. It helps to measure free estriol (one of the main markers of a woman’s and her future baby’s condition).
The triple test is a screening test usually performed between 15 and 20 weeks of gestation. It includes not only the estimation of estriol but also that of HCG and blood alpha-fetoprotein. In some countries like France, this procedure is proposed to all pregnant women under the age of 38. It’s important for identifying at-risk pregnancies, the probability of delivering an infant with certain problems, such as:
- Down syndrome (DS or DNS), also known as trisomy 21;
- aneuploidies, including other trisomies, and polyploidies;
- spina bifida (there are three types of it: spina bifida occulta, meningocele, and myelomeningocele);
- anencephaly (an anencephalic baby is usually blind and deaf due to the absence of a significant portion of the brain);
- a deficiency of the abdominal wall.
This information can help women and their doctors in deciding whether to do diagnostic tests such as amniocentesis (amniotic fluid test) or choriocentesis (chorionic villi sampling). Genetic counseling is usually recommended if this test is positive.
The Bottom Line on Estradiol vs Estrogen
Well, is estradiol the same thing as estrogen? These definitions don’t mean analogous things. In fact, estradiol is estrogen or hormone, belonging to the estrogen group. This female sex hormone is the most active one.
Low estrogen levels (as well as low progesterone levels) induce a deterioration of a woman’s health. Subsequently, it’s extremely important to consult a qualified doctor and take a blood test if you experience symptoms of low estradiol levels.