17-beta estradiol (estradiol) is a form of oestrogen, a female sex hormone produced mainly in the ovaries. Males produce estradiol as well, but at much lower levels and non-cyclically.
In females, estradiol aids in the formation of secondary sex characteristics such as breast development and regulation of the menstrual cycle. In males, it helps govern sperm maturation and on a much smaller scale, reproductive function. While primarily viewed as a female hormone, estradiol has many nonreproductive influences on various physiological systems including brain development, blood coagulation and bone growth.
The Menstrual Cycle
During childbearing years, estradiol is the primary circulating oestrogen. In the first two weeks of the menstrual cycle, estradiol levels stay at low levels. Right before ovulation, levels spike; then after ovulation occurs, sharply drop. Though a bit higher than at the beginning of the cycle, estradiol then remains low until menstruation begins.
Laboratory detection of estradiol can be performed from either blood or saliva specimens. Testing is based on an antigen-antibody reaction. Results help health care professionals assess, treat and monitor conditions such as infertility, menstrual disorders and menopause symptoms in women and hormone imbalances in men.
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