What is estradiol?

Estradiol is the strongest of the three estrogen hormones and is one of the most important hormones in a woman for a healthy and normal menstrual cycle, ovulation, and fertility. Estradiol is naturally produced in both genders with much higher levels in females. It is predominantly produced within the ovarian follicles, but also in other tissues, such as the adrenal glands, fat, liver, breasts, brain, testes, and placenta (during pregnancy) (1).

What are the roles of estradiol in females?
The primary function of estradiol in females is to mature and maintain the reproductive system, including the mammary glands, uterus, and vagina. During each menstrual cycle, estradiol levels increase to trigger the maturation and release of the egg, and the thickening of the uterus lining to allow a fertilized egg to implant (1).

Other roles for estradiol include the development of female secondary sexual characteristics, (such as breasts, female fat distribution, and pubic hair) and increasing both bone and cartilage density. In addition, estradiol affects skin health, the brain, and the musculoskeletal and cardiovascular systems (2).

What are the roles of estradiol in males?
Although estradiol is considered a female sex hormone, it is also important in males. Within the testes, some testosterone is changed into estradiol to aid in the development of healthy sperm, as well as modulate libido, and for normal erectile function (3). It also has many of the same effects in males as it does in females, including an influence on skin health, the brain, and the musculoskeletal and cardiovascular systems (2).

What are normal estradiol levels?
Estradiol levels vary throughout a person’s lifetime, so there are wide variations in what is considered the normal reference levels.

Both girls and boys have low estradiol levels during childhood, although girls do have higher levels than boys even before physical signs of puberty. Prepubertal girls have estradiol levels of 1.6 +/- 2.6 pg/mL, while prepubertal boys have estradiol levels of 0.4 + 1.1 pg/mL (4). At puberty, estradiol levels gradually increase.

In females of reproductive age, estradiol levels rise and fall twice during each menstrual cycle. At the beginning of the follicular phase of the cycle (when menstruation occurs), estradiol levels are low (25–75 pg/mL). Levels gradually increase, until a rapid increase to 150–750 pg/mL just before ovulation occurs (when an egg is released), followed by a rapid decrease. During the luteal phase, estradiol levels gradually increase again to around 30–450 pg/mL, preparing the uterus for possible fertilization. If the released egg is not fertilized, estradiol levels decrease again to basal levels and menstruation begins (5). However, if the egg is fertilized for a pregnancy, estradiol levels keep increasing, until they reach levels as high as 40,000 pg/mL during the third trimester (6).

As females age, their estrogen levels slowly decrease, until a large decrease at menopause. Postmenopausal women generally have estradiol levels less than 20 pg/mL (5).

Normal estradiol levels in adult males are 10–50 pg/mL (5).

What happens if estradiol levels are too high?
In females, elevated estradiol is associated with (1):

  • Acne
  • Constipation
  • Decreased libido
  • Depression
  • Weight gain
  • Fertility issues
  • Increased risk of uterine and/or breast cancer

In males, elevated estradiol can cause (1):

  • Sexual dysfunction
  • Loss of muscle tone
  • Increased body fat
  • Development of breast tissue

What happens if estradiol levels are too low?
Low estradiol is associated with (1):

  • Skeletal issues (e.g., inadequate bone growth and osteoporosis)
  • Delayed puberty, disrupted menstrual cycle, and infertility in females
  • Fertility issues in males
  • Depression
  • Fatigue
  • Mood swings

How can I measure my estradiol levels?
We offer several different tests to measure your estradiol levels. These tests just require a small blood sample collected from a simple finger prick in the privacy of your own home. Test results are available through our online portal, thereby avoiding the need to make any doctor or lab appointments. Of course, you may also wish to discuss your results with your healthcare professional, and this is highly recommended if you receive any results that fall outside the normal range.

The Estradiol (E2) test measures just your estradiol levels. For females of reproductive age, it is helpful to know what stage of your menstrual cycle your sample was collected at, as normal levels vary throughout each cycle.

There are various combination tests available for females that include estradiol along with other important hormones:

Males may wish to order the Estradiol (E2) test (estradiol alone) or the Men’s Health Hormone Panel (6 biomarkers), which includes estradiol along with other hormones that are important for male health.

1. Oestradiol. You and your Hormones, an education resource from the Society for Endocrinology. Reviewed Mar 2018.
2. Estrogen’s Effects on the Female Body. John Hopkins Medicine.
3. Schulster M, Bernie AM, Ramasamy R. (2016) The role of estradiol in male reproductive function. Asian J Androl. 18(3):435-40.
4. Janfaza M, Sherman TI, Larmore KA, Brown-Dawson J, Klein KO. (2006). Estradiol levels and secretory dynamics in normal girls and boys as determined by an ultrasensitive bioassay: a 10 year experience. J Pediatr Endocrinol Metab. 19(7):901-9.
5. Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic & Laboratory Test Reference. 14th ed. St. Louis, Mo: Elsevier; 2019.
6. Speroff L, Glass RH, and Kase NG. (1994). The Endocrinology of Pregnancy. In: Mitchell C, editor. Clinical Gynecologic Endocrinology and Infertility, 5th ed. Baltimore: Williams and Wilkins. 251-289.