What is estradiol?

Estradiol (E2), a type of estrogen hormone, is naturally produced by both males and females. In females, estradiol regulates the menstrual cycle, plays a role in fertility and ovulation, and can indicate the presence of PCOS. In males, this hormone is important for modulating libido, erectile function, and sperm synthesis. Estradiol also operates beyond the reproductive system, including bone health and brain function.

Why is it included in the Balance Axis?

Because estrogen is the primary reproductive hormone for females, estradiol (the most potent type of estrogen) is included in SiPhox Health's base panel for females. Global Women's Medicine mentions that elevations in estradiol may indicate pregnancy or ovulation, but could also point to underlying conditions such as tumors, PCOS, or liver disease. Decreases in estradiol may indicate menopause, but could also point toward pituitary, adrenal, or ovarian failure. Osteoporosis (loss of bone mass) occurs frequently with estradiol deficiency, which could be alleviated by hormone replacement therapy.

Since it is also important for male reproductive health as described above, estradiol is included in the male Hormone+ panel as well. According to a 2020 study, men with abnormally high estradiol levels have been associated with erectile dysfunction while abnormally low levels reported low libido and sexual activity. Besides sexual dysfunction, abnormally high estradiol levels are also linked to loss of muscle mass, fatigue, mood swings, abdominal obesity, cardiovascular disease, insulin sensitivity, blood sugar dysregulation, and even enlarged breasts.

How can I better understand my results?

Estradiol tests should be taken on day 3 of your menstrual cycle. When interpreting results for estradiol, it is important to consider how dynamic this hormone can be. In menstruating folks, estradiol varies considerably between the follicular and luteal phases of the menstrual cycle. During perimenopause (the start of menopause), estradiol levels start to decline, and postmenopausal (after menopause) levels remain low with minimal fluctuation. In males, estradiol is low and is relatively static as well.

The following graph by Straight Healthcare shows how variable estradiol can be for menstruating females, along with other hormones that are important for the regulation of the menstrual cycle.

Female hormone physiology

To assist in the interpretation of test results, the American Board of Internal Medicine published reference ranges for estradiol:

Normally Menstruating Females: 

  • Follicular phase: 10 - 180 pg/mL
  • Mid-cycle peak: 100 - 300 pg/mL
  • Luteal phase: 40 - 200 pg/mL

Postmenopausal Females:

  • < 10 pg/mL


  •  20 - 50 pg/mL

For postmenopausal females who are on hormone replacement therapy, an estradiol range between 50-100 pg/mL can be expected. SiPhox Health results in the 1000s of pg/mL may be indicative of an underlying issue, or may be caused by creams containing bioactive compounds. Some creams contain compounds that mimic naturally produced hormones. Avoid touching bioactive creams with your hands for 48 hours before the test. It is also essential to thoroughly wash your hands with warm water and soap prior to collection. You should consult your physician if your hormonal result persists on repeat testing.

If your estradiol levels are elevated, you can try:

  • Lowering your body fat percentage
  • Managing stress
  • Abstaining from alcohol
  • Increasing magnesium and fiber consumption to improve liver function

If your estradiol levels are low, you can try:

  • Consuming foods high in phytoestrogens (fruits, grains, nuts, seeds, soy, veggies)
  • Obtaining sufficient amounts of boron, vitamin B, vitamin D, and vitamin E
  • Taking natural supplements including black cohosh, DHEA, and red clover

If you are concerned with any of your results, please consult with your physician to seek guidance.

Where can I learn more?

Read Mount Sinai’s synopsis of their estradiol tests.

National Institutes of Health - Estradiol

Straight Healthcare - Female Hormone Physiology