Compounded bioidentical hormones in the USA typically contain a large quantity of estriol, a weak estrogen. The rationale for this is that rats pretreated with estriol developed less breast cancer ...

These creams often contain estriol and are not approved by the Food and Drug Administration. Because they are not regulated, ...

[20] Estrone has a binding affinity for ER-α of 60 and for ER-ß of 37. Estriol binds to ER-α with an affinity of 14 and to ERß with an affinity of 21. Therefore, estradiol has the strongest ...