A quick crash course: hormone replacement therapy generally refers to one or more of these three hormones.  Here’s what they do and why we care.

  • Estrogen: there are estrogen receptors in just about every part of a woman’s body.  Estrogen contributes to health of the urinary tract, bones and muscles, blood vessels, skin and vaginal tissue.  But, there can be too much of a good thing: estrogen dominance (relative to progesterone) leads to symptoms like PMS, mood swings, cramping, fluid retention, fibroids and heavy bleeding, low libido, elevated cholesterol and triglycerides.
  • Progesterone: this helps to prepare the uterine lining for implantation, and so it begins to rise just prior to ovulation.  Progesterone and estrogen decline together throughout the second half of a woman’s menstrual cycle, and if the two are in balance, the symptoms associated with estrogen dominance should not occur.
  • Testosterone: Women produce about 1/20 the amount of testosterone that men produce.  Testosterone contributes to healthy libido, a sense of well-being and vitality, and healthy bones and muscles.  When a woman is estrogen dominant, she may be clinically deficient in testosterone even if her blood levels of total testosterone are normal, since estrogen produces a protein called Sex Hormone Binding Globulin (SHBG).  This protein binds testosterone, rendering it unavailable to the cells for use.  (That’s why it’s useful to check not just total testosterone on blood tests, but free testosterone.  This gives you a more complete clinical picture.)


Until July 2002, these were the standard treatment for menopausal symptoms.  However, the Heart and Estrogen/progestin Replacement Study (HERS) and Women’s Health Initiative (WHI) clinical trials illuminated the health risks associated with synthetic hormones, listed below. (Bioidentical hormones, however, were not included in these trials, and do not carry the same risks.)

  • Premarin: prepared from pregnant horse urine, these are conjugated estrogens, and they are not biologically identical to those produced in the body – which means they do not follow normal human metabolic pathways.  They are associated with vaginal bleeding, high blood pressure, blood clots, stroke, heart disease, nausea, vomiting, headaches, fluid retention, and they may increase the risk of estrogen receptor positive cancers.
  • Progestins: these synthetic progesterone molecules are less effective than bioidentical progesterone, and can cause side effects such as abnormal menses or loss of menses, nausea, depression, weight changes, fluid retention, and insomnia.
  • Methyltestosterone: this synthetic analog of testosterone puts added stress on the liver, and is correlated with liver damage and liver cancer.  The body does not recognize it, so it is not possible to correlate clinical effects of methyltestosterone with blood levels of testosterone.


Bioidentical hormones are still prepared in a lab, but the molecules themselves are identical to those produced in the body (hence the name).  I still don’t prescribe bioidentical hormones first for most women – sometimes a healthy lifestyle and supplement regimen is all it takes to alleviate symptoms of estrogen dominance or menopause.  For others, though, bioidentical hormone prescriptions will depend upon the individual’s blood levels of each of the hormones, as well as her symptoms.

  • BiEst or TriEst: there are three bioidentical estrogen molecules, called estrone (E1), estradiol (E2), and estriol (E3).  Estrone is not active in the body – it simply converts into estradiol.  Estradiol is the one that is most beneficial in alleviating symptoms, but it is also the one implicated in estrogen receptor positive cancers.  There is some evidence that estriol is actually protective against these estrogen receptor positive cancers.  For this reason, BiEst is a compounded formula of just estradiol (20%) and estriol (80%), while TriEst contains all three.  TriEst is considered to be the safest for women with a family history of cancer, since it contains only 10% estradiol.
  • Bioidentical Progesterone: prepared from extracts of wild yam or soybeans, these counterbalance estrogen dominance symptoms, help lift mood, restore libido (by counterbalancing estrogen), improve memory, assist with sleep, and protect against endometrial cancer.  They may, however, alter the timing of the menstrual cycle for women who are still menstruating.
  • Bioidentical Testosterone:  unlike methyltestosterone, it is possible to correlate blood levels with clinical activity for this one.  I usually prescribe this only when both the symptoms and blood levels agree. Since testosterone is a controlled substance, women whose prescription includes testosterone must have blood levels checked every six months, as opposed to yearly for just estrogen and progesterone.  It is possible to overdose on testosterone – symptoms of overdose include aggression and irritability, acne, and abnormal hair growth.
  • DHEA: this is a parent hormone for both testosterone and the estrogens, and it is produced by the adrenal glands (one reason why adrenal health is so important for menopausal women!)  Also, patients who have been on steroids (such as prednisone) for a long time will almost certainly be low in DHEA, since the two are opposed to each other.  DHEA is available over the counter, although I recommend having your levels tested before you supplement with it, since overdose may result in some of the testosterone overdose symptoms mentioned above.