Also spelled as estradiol, is an estrogen steroid hormone produced from cholesterol. The strongest of naturally produced oestrogens, oestradiol, is the main oestrogen present in women.

While oestradiol has several functions, the primary purpose is the regulation of the female reproductive cycle. When women have a period, the blood oestradiol concentration increases which helps in ovulation of the eggs.

Another essential function of oestradiol is to thicken the uterine lining to allow the implantation of the fertilized eggs.

Oestradiol helps in developing and maintaining female reproductive organs like mammary glands, vagina, and uterus during a woman’s puberty, adulthood, and pregnancy.

It also helps in the development of secondary female sexual characteristics like female-specific fat distribution and widening of hips.

During the premenopausal phase, levels of oestradiol, produced by ovaries, vary. It is at its peak during ovulation and at its lowest during menstruation.

As a woman ages, the oestradiol levels start reducing, with a significant dip happening during the menopause, where the ovaries stop producing eggs.

In pregnant women, oestradiol is also produced in large quantities by the placenta.
Oestradiol is also produced in men, but the quantities are much lower. Some amount of testosterone present in testes changes into oestradiol, which plays a significant role in the production of sperm.

In both sexes, the fat tissue, the blood vessel walls as well as the brain also produce oestradiol, but it is in much smaller quantities.

Hormones Involved in Controlling Oestradiol

Hormones released by the pituitary gland and the hypothalamus have a significant role to play when it comes to controlling the production of oestradiol. It is also known as the reproductive axis in females (hypothalamus-pituitary–ovary).

The hypothalamus releases gonadotropin-releasing hormones that act on the pituitary gland. This results in the release of two additional hormones - follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

FSH and LH enter the bloodstream and ensure stimulation of ovary. The FSH and LH act on cells surrounding the egg and encourage the follicle to grow as well as develop.

Oestradiol is produced by the cells in the last phase of growth and development. Once the egg ovulates, the ovulated follicle becomes corpus luteum.

The corpus luteum produces progesterone as well as oestradiol. The primary role of these hormones is developing and preparing the uterine lining for implantation, if the eggs fertilize.

The oestradiol and progesterone levels allow the hypothalamus and pituitary gland to control the development of the egg, as well as ovulation and menstrual cycle.

Excess Oestradiol Production

The production of oestradiol varies. Sometimes, the body develops too much oestradiol, which can have numerous side effects.

Minor side effects of excess oestradiol production include constipation, development of acne, depression, and loss of libido.

More severe effects can include weight gain, increased risk of heart attack, stroke, female infertility and increased chances of developing breast/uterine cancer.

Increased production of oestradiol in men can result in sexual dysfunction, increased body fat, development of breast tissue, and loss of muscle tone.

As man ages, oestradiol production increases, and while the testosterone production reduces, which can, according to some scientists, result in prostate cancer.

Too Little Oestradiol

Oestradiol is one of the primary components in bone development, so any decrease in oestradiol can result in skeletal problems such as osteoporosis and stunted bone growth.

Girls with low oestradiol levels can have problems during puberty like either a delay or failure in the development of mammary glands, a disruption in, or absence of, menstrual cycle as well as infertility.

Oestradiol also performs significant functions in the brains, so people with low oestradiol levels can have fatigue, mood swings, and depression.

As woman ages and reaches menopause, the oestradiol production starts falling. Low oestradiol levels are the leading cause of many menopausal symptoms.

Short-term side effects include mood swings, hot flushes, night sweats, and vaginal dryness. In the long term, a woman is at increased risk of developing osteoporosis.

These symptoms can be relieved by hormone replacement therapy.

Synthetic Oestradiol

Synthetic form of progesterone and oestradiol are present in COCP (combined oral contraceptive pill) or more commonly known as “the pill.”

When a woman takes this pill, she does not ovulate, making it the most effective contraceptive ever.

Besides preventing ovulation, the pill also thickens the cervical mucus, which makes the movement of sperm more challenging which, in turn, reduces their chances of reaching the uterus and fertilizing the egg.

Oestradiol is also used in hormone replacement therapy, which helps in addressing the menopausal symptoms.[/QUOTE][/QUOTE]