Hi jorainbow, we discussed the situation with systemic absorption of vaginal oestrogen on Ann B's thread on vaginal oestrogen post breast cancer a few months ago. I've just posted on that thread again so it's back up in current pages if you'd like to look at it. It's quite long so I'll paste in some extracts below in case you don't have time to check it out . . .
In the initial weeks of use, some of the ostradiol in Vagifem does go into systemic circulation. The initial systemic absorption is thought to be because the vaginal mucosa, when in poor condition from atrophy, provide less of a barrier than once improved following adequate oestrogenisation from the effects of the vaginal HRT.
As an example & please bear in mind this is only my personal experience, after an enforced break from vaginal oestrogens of 8 weeks, the blood tests I had coincidentally arranged at the end of the 2 week Vagifem re-loading period showed my systemic oestradiol had almost doubled on the value I'd been getting from my systemic (patch based) HRT. We could think of no other explanation than that the increase was due to the cumulative load from the nightly 10mcg oestradiol in Vagifem.
There are some articles & extracts here:-
Position Statement for Management of Genitourinary Syndrome of the Menopause (GSM) https://balance-menopause.com/uploads/2021/10/GSM-for-BSSM-FINAL-version-with-links.pdf"The dose of vaginal oestrogen is very low; for example, using 10mcg oestrogen pessaries regularly for one year is an
equivalent dose to just one 1mg of oestradiol HRT tablet."
The following paper mentions that placement (depth of insertion within the vagina) may influence how much gets into systemic circulation. You will need to read the detail in the paper, but it seems that shallower insertion may result in less systemic absorption.
It also touches on absorption diminishing over time as the condition of the vaginal mucosa improves in response to the local treatment.
Systemic estradiol levels with low-dose vaginal estrogenshttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC7050796/"Systemic estradiol absorption may be influenced by the placement of estradiol higher (as with an applicator) versus lower (as without an applicator) in the vagina . . . From this evidence, the authors recommended placing vaginal estrogens in the outer third of the vagina to reduce the risk of estradiol transport to the uterus. In addition, lower estradiol absorption was observed with softgel capsule vaginal inserts placed without an applicator (lower in the vagina) versus tablet vaginal insert of the same doses inserted with an applicator (higher in the vagina) in a head-to-head study. Taken together, these data support a difference in estradiol absorption depending on placement of an estrogen product in the vagina."
"Thickness of the vaginal wall due to response with estrogen treatment may affect systemic absorption of estradiol when estrogens are used locally in the vagina. Some studies that measured estradiol levels at different times after vaginal estrogen use showed that peak and/or average levels declined over time as vaginal wall thickness likely increased with treatment"
"Certainly, after longer-term vaginal estrogen treatment (12 weeks, 83 or 84 days, 52 weeks), levels of circulating estradiol were similar to those at baseline or with placebo"
"CONCLUSIONS
Our review of systemic absorption of estradiol with use of low-dose and ultralow-dose vaginal estrogen therapies found low to negligible amounts of circulating estradiol that may be influenced by product formulation and vaginal placement."
Jorainbow I think the advice on lower placement may be particularly relevant for you.
I hope there's something helpful in this.
Wx