Published in October 2009, this LifeExtension Report asks the question, “Why are bioidentical hormones still controversial?” This is an in-depth report on the debate between the use of bioidentical hormones versus their synthetic counterparts. The debate within the debate is the use of estriol versus estradiol in the treatment of estrogen deficiency. Some believe estriol is preferred over other estrogens for treatment whereas others, and the FDA, contend estriol may have long term adverse effects.
Some explanation may be in order: Estrogen (loosely translated from the Greek means “Estros” – sexual desire and “Gen” – to generate or….. to generate sexual desire.) There are three human forms of estrogen:
Estradiol: Is the young female’s hormone of femininity. It’s also called E2. It’s produced by aromatization of Testosterone in the Graafian follicle (granulosa cell). It’s the most potent estrogen with the highest effect on receptors.
Estrone: Is the estrogen of the menopause. It’s produced by aromatization of androstenedione in peripheral (fatty) tissue. It’s also called E1. It’s less potent than Estradiol.
Estriol: Is the placental estrogen and it’s only seen during pregnancy and its high levels reflects fetal well-being. It’s also called E3. It’s the least potent of all estrogens. It originates from the fetal adrenal gland in the form of DHEA Sulfate and then is finally transformed to Estriol in the placenta by the sulfatase enzyme.
Estradiol (E2) is the predominate estrogen used in hormone replacement in the U.S. With respect to administration methods, transdermal versus subcutaneous, subcutaneous pellets have been shown to produce a more steady state of hormones over longer periods of time with greater compliance than other forms of administration.
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This article is thought provoking and a good read. PDF