Hormones and Mood
Estrogen Levels (and the Premarin issue)
The following information
comes from a published letter on measuring estrogen: Shuer
Premarin is derived from
horses, thus the "equine" below. When women take Premarin, they
metabolize the "conjugated equine estrogen" it contains into the
following forms of estrogen: estrone
sulfate, equilin sulfate, 17[alpha]-dihydroequilin sulfate, equilin, equilenin,
17[beta]-dihydroequilin, or 17[beta]-dihydroequilenin.
of these compounds is measured by standard lab tests for
"estrogen" (radioimmunoassay). The form of estrogen produced by
the human ovaries is primarily estradiol, specifically 17[beta]-estradiol.
That can be measured by standard lab tests, and is reported as "estradiol".
But for a women taking Premarin, measuring an estradiol level is like measuring
an imipramine level when a woman is taking Prozac!
which is the synthetic estrogen found in most oral contraceptives, is not picked
up on lab tests for estradiol. In a woman taking an oral contraceptive
(which blocks production of her own estrogen) you can't tell how much estrogen
she's exposed to except by her symptoms, such as excessive uterine bleeding or
breast tenderness -- because the lab test won't measure what she's taking.
the view of Dr. Shuer,Shuer this leads to a
situation in which women can be exposed to high levels of estrogen and yet
there's no simple way to test for that. And therefore the studies of
estrogen risk are being done when we can't measure how much estrogen women are
being exposed to! Thus it does seem odd to think that we've characterized
the risks of estrogen, if we don't know (e.g. in the Women's Health Initiative
study) how much they were getting.