Our hormones are regulated by complex feedback mechanisms - and this is how the pill works when we are fertile by suppressing the menstrual cycle through high oestrogen especially (which inhibits FSH). Once we are post-menopausal though, and especially 2 years following the last ovulation, our ovaries have shut down - at least that part of it which stimulates follicles to grow, ripen and produce oestrogen. They atrophy and seemingly disappear and are often impossible to find on scans - although they are actually still there (they haven't found mine for years - in the last few scans I've had - good sign though as it means there is nothing wrong with them). Once all cyclical activity has stopped ovaries do continue to secrete some hormones - definitely androgens I understand - which ultimately can be converted to testosterone eslewhere in the body, and also to oestrogen though not sure if this actually happens in the ovary or other tissues? The feedback mechanisms no longer happen I don't think because that loop has finished (pause to look up the name...) - hypothalamic gonadal axis - which is the complex endocrine feedback mechanism whereby LH, GnRH , FSH etc are produced and govern ovulation etc. I have to look up the exact details as not in my head!!
Once we are well post-menopause we are doing just that as you say, blithely topping up our hormones.
You mention some women only needing half the dose? Well what is need? Discuss!!! We need whatever we want to control our symptoms and we decide that. We might tolerate a sporadic return of flushes when we are older for example - to minimise the progestogen dose we have to take. We can also wean ourselves onto a lower dose as we get older sometimes. (Think I should start doing that at some point - when I'm 70?). If we want to give protection against osteoporosis then there is a minimum dose to take whatever we feel.
I don't think that helps at all does it? Saturday night ramble after a small glass of wine!!!
Interesting question anyway Kathleen!!!
Maybe Dr Currie could answer and it would certainly be clearer than mine!!!
Hurdity x