I think you're on the right track there Kate.
Its very rare when people switch from pills to injections that the serum level will
be exactly the same, so saying one is better than the other is like comparing
apples and oranges.
Doctors tend to rarely prescribe high enough dosages
of pills because of the misguided notion (in my opinion) that its hard on the liver.
They seem to confound non-bio identical estrogens like premarin and ethinilestradiol,
with those that are bio identical.
They seem to also totally forget that they can be used sublingually.
There is a correspondence table between pills and injections,but this is an
area which has not been studied at all and I don't even know where those
tables come from!
So, when they prescribe injections which are more liver friendly, they might
boost the doses. But, since we're not comparing actual numbers here I can't say
for sure what doctors prescribe here, just what I know from TS acquaintances on
my side.
And yes, everything has a baseline genetic sensitivity to E.
This sensitivity even varies with the amount of T and P and the level of E in the body,
plus a few other feedback mechanisms. How much tissue growth or fat transfer
you get from this sensitivity is influenced by multiple metabolic factors (insulin and human growth hormone
levels for example).
So, it is impossible at first hand to know how sensitive you are and what results you'll get
from this sensitivity, though its possible to guess
from familly genetics and your own body.
If you're at a normal weight and
you've got very little fat in the gynoid areas, thigh and legs, prior to HRT, your response
to estrogen is likely lower (not zero, so nobody jumps on me)
than someone who's got a good cover of fat there even if skinny.
I've seen both versions at a party this summer, there were some with years of HRT
who had muscles well defined on their legs with little fat on them (and they were not that athletic or skinny) and others with no visible muscle definition because of fat coverage who were athletic (one was an university athlete).