MaryG, now 9 years postmenopause & as a fellow migraineur & life-long IBS-C sufferer I'm also very interested in the role sex hormones play in functional gut disorders & migraine. I find the opposite effects from higher doses of oestrogen to those you've experienced, i.e. increasing my oestradiol dose slows gut transit, thereby worsening my pre-existing IBS-C. Those of us with migraine tendencies do seem to also be more prone to digestive dysfunction & as both conditions can be profoundly affected by HRT, I think our need for replacement can be especially difficult to manage.
I posted a link to a study some time ago in the long-running "Poo" thread, that found that oestrogen (as well as has been long known - progesterone) delays rather than increasing rate of gastric emptying. I'm not citing this to contradict your experience, rather to agree that in my experience sex hormones can have profound effects on the GI tract & I can absolutely believe your gut is also highly sensitive to the effects of HRT. I won't post the link here as it's not relevant to your main point that we should be open to the possibility our postmenopausal HRT needs may change with advancing age. That point I think is also well made. I'm struggling to get my HRT right approaching 60 & though I feel better in most ways on 37.5mcg - 50mcg oestradiol, the one problem that may prove the deal-breaker for me is that no amount of dietary care, exercise, fluid etc, together with other life-long coping strategies for managing the IBS-C, compensate for the paralysing opioid-type effect oestrogen seems to have on my digestive tract. On 25mcg oestradiol I don't feel the systemic benefits I get on higher doses & really need, but my slow gut transit is more manageable.
The smooth muscle relaxant effect of progesterone further exacerbates the IBS-C for me, but that's another chapter & not for this thread!
For anyone who's interested & in support of our gut-related experiences I'm posting the following link & extracts.
I'm pleased to know reducing your HRT slightly seems to have had a fairly immediate beneficial effect & I hope you continue to feel well on the lower dose as you go further into postmenopause.
https://abdominalkey.com/female-predominance-in-gastroparesis/"It is well established that female sex hormones (i.e. estrogen, progesterone) play a critical role in reproductive health. Nevertheless, emerging evidence demonstrates that sex hormones can also influence GI motility, with estrogen and progesterone receptors found throughout the GI tract."
"Nonpregnant women who received exogenous estradiol and/or progesterone to levels equivalent in the first trimester of pregnancy also experienced nausea with similar dysrhythmias evoked on electrogastrography. This suggests that elevated levels of progesterone and estrogen can mimic GI symptoms experienced during pregnancy and may concomitantly cause gastric dysrhythmias."
"Estrogen, in particular, interacts with serotonin and augments the serotonergic postsynaptic responsiveness in the brain . Serotonin can therefore mediate the effects of estrogen which further influences depression, pain transmission, nausea, headaches and dizziness in the CNS . Hence, sex hormones modulate different levels of the brain-gut axis in IBS and contribute to alterations in motility"
Wx