What about HT for younger women?

The menstrual cycle can stop at a young age. In some women this happens because they had their ovaries surgically removed, but radiation or chemotherapy treatment for cancer, or other medical conditions can also stop the ovaries from working. In many women there is no single explanation for why the ovaries stopped functioning at a young age. This is not called menopause, it is called either “premature ovarian insufficiency”, or “premature ovarian failure”.

Women who lose ovarian function at a young age will normally be advised to have their hormones replaced for the health of their heart, bones and brain. This is particularly important for women who experience premature ovarian insufficiency who are younger than 40.