Hi Hurdity, yes it's very interesting/perplexing I agree.
I'm not sure whether I can or should name names of doctors, but someone who has previously written extensively about tachyphylaxis told me 'it doesn't exist', then put the phone down.
And someone else closely linked to him said of my problem 'it's tachyphylaxis'. (And it didn't need to be supraphysiological levels').
It doesn't really matter what it's called, what I am experiencing is a lack of response after repeated administration. And I believe it's more common than consultants might admit.
Yes to your point about exogenous estrogen vs our own estrogen, that is indeed puzzling. Maybe bioidenticals aren't as identical as everyone thinks? Or there's some other reason - too much constant repeated stimulation for too long? Perhaps the body prefers cyclical variation. Don't know, obviously these are all guesses.
I know you've used estrodot for years without problems, so I bet it's hard to imagine it not working. I would have found it really, REALLY hard to believe before, but there's no doubt in my mind that it happens - now it's happened to me. It's not just psychological changes, I have very obvious physical meno changes while on HRT and at high plasma levels. x