oophorectomy
"I have been taking Premarin for (the better part of) 25 years. Due to insurance changes through this time I've been directed to use other estrogens. I will emphatically state that there is NO substitute for premarin. The others gave me breakthrough hot flashes and PMS.  With all of the plumming gone, these were not acceptable being 32 years old. 

Premarin every day has kept me at an steady keel with no wavering in mood or temprament."