Most physicians lump all hormones into the same bucket.

Despite most physicians lumping all hormones into the same bucket, we want to once again explain that there is a stark difference between bio-identical estradiol and conjugated equine estrogen (created from horse urine) hormones.  While we prefer estradiol as the estrogen of choice, esterified estrogens are precursors for estradiol and have been studied as a means of hormone replacement.  This study compared the risks of blood clot formation in patients taking esterified estrogen vs conjugated equine estrogen vs placebo.  They conclude that conjugated equine estrogen but not esterified estrogen was associated with venous thrombotic risk and may have implications for the choice of hormones in perimenopausal and postmenopausal women.

Smith, N.L, et.al. JAMA. 2004 Oct 6;292(13):1581-7. 

Clot formation happens with synthetic hormones and not with bio-identical forms!

Jason & Rita