Ovarian daily production of Estradiol per day is 70-500 mcg (0.5 mg)

After menopause most endogenous estrogen is produced by conversion of Androstendione via adrenal cortex, to Estrone by peripheral tissues

Estrogen is bound to SHBG (sex hormone binding globulin)

Estriol is major urinary metabolite

Single intramuscular injection of estrogen is metabolized over several weeks

Estradiol and Estrone are reversibly converted, hence the reason why women who have high body fat (indicative of high Estrone) often are
symptom free

To date two estrogen receptors have been identified which vary in proportion from tissue to tissue

Carbamazepine (Tegretol) and St. John’s Wort decrease plasma estrogen

Inhibition of CYP3AY such as Erythomycin, Ketoconazole (Nizoral), grapefruit juice – all increase plasma concentration of estrogen

Estrogen increases TBG – hence, may require low dose physiologic thyroid replacement