For example, the estrogens obtained from the urine of pregnant mares is not totally identical with estrogen produced by humans. And although the use of these "mare" hormones by women will not have them breaking out into spontaneous whinnies, as some comedians have portrayed, they have caused some women to experience other side effects. These include excessive water retention, headaches, and moodiness.

There are also synthetic hormones produced by drug companies that are available. These designer hormones are generally not identical, at the molecular level, with those natural hormones produced in the body. Synthetic estrogen receptor modifiers (SERMS) will have a place in future treatment.

Finally, there are natural versions of both estrogen and progesterone available. These forms of the hormones are identical, at the molecular level, with those produced in the body. And in general, women taking the natural versions of either progesterone or estrogen, have tended to report fewer unpleasant side effects.

We generally use natural estradiol or combinations with estriol when needed and we use Prometrium (micronized natural progesterone) or progesterone cream applied at night to various body sites. Often the natural cycle of estrogen and progesterone will be maintained to mimic premenopausal cycles and many women feel better with this approach. Saliva levels or blood levels are always followed for proper replacement techniques.

Again, as with any hormone replacement therapy, estrogen and progesterone therapy should be carried out only under the direct care and supervision of a medical doctor.