Effects

Female reproduction

In the female, estradiol acts as a growth hormone for tissue of the reproductive organs, supporting the lining of the vagina, the cervical glands, the endometrium and the lining of the fallopian tubes. It enhances growth of the myometrium. Estradiol appears necessary to maintain oocytes in the ovary. During the menstrual cycle, estradiol that is produced by the growing follicle triggers, via a positive feedback system, the hypothalamic-pituitary events that lead to the luteinizing hormone surge, inducing ovulation. In the luteal phase estradiol , in conjunction with progesterone, prepares the endometrium for implantation. During pregnancy estradiol increases due to placental production. In baboons, blocking of estrogen production leads to pregnancy loss suggesting that estradiol has a role in the maintenance of pregnancy. Research is investigating the role of estrogens in the process of initiation of labor.

Sexual development

The development of secondary sex characteristics in women is driven by estrogens, specifically estradiol. These changes are initiated at the time of puberty, most enhanced during the reproductive years, and become less pronounced with declining estradiol support after the menopause. Thus, estradiol enhances breast development, and is responsible for changes in the body shape affecting bones, joints, fat deposition. Fat structure and skin composition are modified by estradiol.

Male reproduction

The effect of estradiol (and estrogens) upon male reproduction is complex. Estradiol is produced in the Sertoli cells of the testes. There is evidence that estradiol is to prevent apoptosis of male germ cells.

Several studies have noted that sperm counts have been declining in many parts of the world and it has been postulated that this may be related to estrogen exposure in the environment. Suppression of estradiol production in a subpopulation of subfertile men may improve the semen analysis.

Males with sex chromosome genetic conditions such as Klinefelters Syndrome will have a higher level of estradiol.

Bone

There is ample evidence that estradiol has a profound effect on bone. Individuals without estradiol (or other estrogens) will become tall and eunuchoid as epiphysieal closure is delayed or may not take place. Bone structure is affected resulting in early osteopenia and osteoporosis. Also, women past menopause experience an accelerated loss of bone mass due to a relative estrogen deficiency.

Liver

Estradiol has complex affects on the liver. It can lead to cholestasis. It affects the production of multiple proteins including lipoproteins, binding proteins, and proteins responsible for blood clotting.

Brain

Estrogens can be produced in the brain from steroid precursors. As an antioxidant, they have been found to have neuroprotective function.

The positive and negative feedback loop of the menstrual cycle involve ovarian estradiol as the link to the hypothalamic-pituitary system to regulate gonadotropins.

Blood vessels

Estrogen affects certain blood vessels. Improvement in arterial blood flow has been demonstrated in coronary arterie.

Estradiol Test

An estradiol test measures the amount of a hormone called estradiol in the blood. Estradiol is the most important form of estrogen found in the body. Most of it is made in and secreted from the ovaries, adrenal cortex, and placenta.

Estradiol is responsible for the growth of the female uterus, Fallopian tubes, and vagina. It promotes breast development and the growth of the outer genitals. The hormone plays a role in the distrubtion of body fat in women and stops the process of growing taller.

How the Test is Performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Why the test is performed

This test is used to check the function of the ovaries, placenta, or adrenal glands, particularly when certain types of ovarian tumor are suspected, or when there is delayed or abnormal development of male or female body characteristics.

Women undergoing assisted reproductive technology (ART) for infertility may have this test at regular intervals in combination with ultrasound imaging to monitor their ovaries’ response to stimulation.

What abnormal results mean

Greater-than-normal levels may indicate ovarian tumor.

Lower-than-normal levels may indicate Turner syndrome.

The test may also be used to monitor patients with hypopituitarism and women undergoing certain fertility treatments.

Sources: NLM NIH, CEBP AACRJOURNAL

Related Posts