When can progesterone be added in the treatment of estradiol for women with an intact uterus?

For women with an intact uterus, the addition of progesterone is crucial when they are undergoing estrogen therapy. This is because estrogen alone can stimulate the endometrial lining, increasing the risk of endometrial hyperplasia and potential malignancy. Progesterone's role is to counteract this effect by inducing a cyclical shedding of the endometrial lining, thereby providing protective effects against these risks.

The correct approach for integrating progesterone into the treatment protocol is for a specific duration each month. The standard is to administer progesterone for 12 to 14 days each month, typically in conjunction with estrogen therapy. This cycling mimics the natural hormonal fluctuations of a menstrual cycle, ensuring that the endometrium is sufficiently managed.

This regimen does not necessitate the use of progesterone only in response to specific symptoms like hot flashes or based on estrogen levels. It also does not require continuous application throughout the month, as that would not align with the goal of managing the endometrium appropriately while providing the benefits of both hormones.