In Detail
The most important difference is molecular structure. Traditional hormone therapy historically used conjugated equine estrogens (derived from pregnant mare urine) and synthetic progestins like medroxyprogesterone acetate. Bio-identical hormone therapy uses estradiol and micronized progesterone — molecules identical to what the human body produces.
The clinical implications matter. Micronized progesterone has a more favorable safety profile than older synthetic progestins, particularly with respect to breast tissue and cardiovascular markers. Transdermal estradiol bypasses first-pass liver metabolism, which lowers the risk of blood clots compared to oral estrogen.
Delivery methods also expand the options: patches, gels, creams, oral capsules, vaginal preparations, and pellets allow individualization based on symptoms, preferences, and clinical considerations.