Estrogens actually refers to
a group of related hormones, each with a unique
profile of activity. Under normal circumstances,
a woman’s circulating estrogen levels fluctuate
based on her menstrual cycle. For Hormone Replacement
Therapy, these hormones are often prescribed in
combination to re-establish a normal physiologic
balance. The three main estrogens produced in female
humans are:
•
Estrone -E1-
(10-20% of circulating estrogens) is the primary
estrogen produced after menopause.
•
Estradiol -E2- (10-30%
of circulating estrogens) is the most potent
and major secretory product of the ovary,
and the predominant estrogen produced before
menopause.
•
Estriol -E3- (60-80% of
circulating estrogens) causes little or no
buildup of the endometrium, and is very effective
in alleviating vaginal and urinary symptoms
in postmenopausal women. Estriol is produced
in very large amounts during pregnancy. High
levels of estriol are found in vegetarians
and Asian women, who have a much lower incidence
of breast cancer.
