Adding vaginal estrogen to a woman already on systemic estradiol therapy will not increase her systemic estrogen levels or add systemic risk, but will significantly reduce UTI rates.

“It doesn't increase if your estrogen level 70 on your patch and you add a vaginal estrogen, her estrogen level is going to stay 70. You're not going to get that systemic absorption, but you are going to reduce your UTI rate significantly.”