Dr. Valentine talks to women about natural hormone replacement therapy.

Hormone replacement therapy (HRT) is now a well accepted way to restore the levels of specific female hormones, including progesterone, to those prevalent during early adulthood. HRT helps to maintain good health and resist the postmenopausal problems of osteoporosis as well as the variety of untoward symptoms experienced by aging women.

This therapy is by no means restricted to postmenopausal women, however. Ten to fifteen years before menopause, women can have anovulatory cycles, in which they are producing estrogen but not progesterone. This can lead to the many unpleasant symptoms associated with PMS. Dr. John Lee, a leading authority on the use of natural progesterone in hormone replacement therapy, refers to this condition as estrogen dominance. Using progesterone cream during these months may help with PMS. Naturally, women are asking a lot of questions about progesterone.


Progesterone is a natural steroid hormone that is found in much higher concentrations in women than in men. It operates harmoniously with estrogen and other steroid hormones involved in physiological functions such as the menstrual cycle and preparing the uterine lining for implantation by a fertilized egg. Other vital roles of progesterone are building new bone tissue and countering the tendency of estrogen to cause excess growth in the lining of the uterus (the endometrium). In extreme cases, this growth can develop into cancer.

Progesterone is a precursor to the hormones estrogen and testosterone. (Estrogen is not actually a single hormone, like testosterone, but a term for a group of related female sex hormones with similar biological activity, mainly estrone, estradiol, and estriol.) If progesterone diminishes, so can these other hormones, which have their own important roles in our physiological health.

A summary of the many roles of progesterone follows:

  1. Promotes bone building and protects against osteoporosis
  2. Improves premenstrual symptoms (PMS)
  3. Protects against endometrial cancer
  4. Helps protect against breast cancer
  5. Precursor of other sex hormones (estrogen and testosterone) and cortisone
  6. Maintains lining of uterus
  7. Promotes survival of the embryo and fetus throughout gestation
  8. Natural diuretic
  9. Promotes fat burning for energy (thermogenesis)
  10. Acts as a natural antidepressant
  11. Aids thyroid hormone action
  12. Normalizes blood clotting
  13. May help maintain sex drive
  14. Helps keep blood sugar levels normal
  15. Normalizes zinc and copper levels
  16. Promotes proper cellular oxygen levels

Commercially sold natural progesterone is, as the name implies, a natural product and has a molecular structure identical to that of human progesterone. By contrast, Provera (one of several trade names for medroxyprogesterone acetate, or MPA) is a synthetic compound that mimics, but cannot duplicate, the actions of natural progesterone. Such synthetic drugs lack many of natural progesterone's important benefits and can cause any number of unpleasant side effects, including an increased risk of heart disease. Unfortunately, the standard practice in American medicine has been to replace the natural hormone progesterone with Provera. The combination of Premarin® (a mixture of estrogenic hormones extracted from the urine of mares) and Provera is the most common form of hormone replacement therapy in the United States.

Recent studies have demonstrated that the use of progesterone in hormone replacement therapy instead of medroxyprogesterone acetate (as typified by Provera) provides better relief from menopausal symptoms and better patient compliance with the therapy; also, the quality-of-life benefits of progesterone therapy, such as how you feel generally, are superior to those obtained from MPA.1

Actually, it's the other way around. If you are taking estrogen, you need to be taking progesterone simultaneously. Taking estrogen alone increases your risk of uterine cancer, but the progesterone decreases this risk dramatically.

The exception to this rule is women who do not have a uterus (usually due to hysterectomy). Such women are traditionally given estrogen replacement therapy without any progesterone (or a synthetic analog) replacement because of the belief that progesterone may be of benefit only for uterine cancer prevention. Whether you have a uterus or not, progesterone offers many benefits besides helping to prevent uterine cancer.

Some women choose not to take estrogen because of its side effects or because it may be contraindicated by an already present estrogen-sensitive cancer, or for personal reasons. These women can still take progesterone alone and receive the many benefits available to them.

It is not necessary to do this in order to start taking progesterone, but it certainly can't hurt. In fact, it's a good idea if preventing osteoporosis or building bone mass is your goal. If you get the test before you start on progesterone or soon afterward, you can repeat it in six months to a year and see how much your bone density has improved; this test may also indicate whether you need to increase the amount you are taking. If, however, you plan to take progesterone for reasons other than osteoporosis prevention or bone building, the bone-density test may be of no interest to you.

Yes. "Transdermal" progesterone means that it is applied to the skin and passes into the subcutaneous fat, the layer of fat just below the skin. From there it enters the bloodstream. This is the only dosing method that approximates the natural, gradual physiological release of the hormone.

There are a number of problems with oral progesterone, including the need to take large amounts of it because of poor gastrointestinal absorption, the tendency for it to be released in surges, and the production of metabolites (substances formed by metabolic processes) that don't function like true progesterone.

It is important that any progesterone cream you buy have at least 400 mg of progesterone per ounce. An application of 1/8 tsp contains about 10 mg; 1/4 tsp is about 21 mg; and 1/2 tsp is about 42 mg.

It is really up to you to experiment with what is the right amount for you, by the measure of how well you feel, and depending on your symptoms or your personal goals, but here are some guidelines:

  • A usual dose for premenopausal women would be 15 to 24 mg (slightly less than or slightly more than 1/4 tsp) per day for 14 days before expected menses, stopping a day or two before menses begins.
  • A dose that works well for many postmenopausal women is 15 mg (slightly less than 1/4 tsp) per day for 25 days each month, following a consistent monthly pattern.

The size of the dab of cream on your skin is not important, because the release of progesterone from the subcutaneous fat to the bloodstream will be relatively steady in any case.

For further information on this subject, I highly recommend both of Dr. Lee's books: What Your Doctor May Not Tell You About Menopause: The Breakthrough Book on Natural Progesterone, and What Your Doctor May Not Tell You About Premenopause: Balance Your Hormones and Life from Thirty to Fifty. Each is an excellent resource, not only on natural progesterone but on women's health care overall.

If premenopausal women are progesterone-deficient, taking the hormone reactivates dormant estrogen receptors. This can cause a buildup of the uterine lining, which may lead to spotting or irregular bleeding. This condition will usually clear up within a couple of cycles. It is also possible for spotting or bleeding to occur in postmenopausal women. This is probably normal, but postmenopause always entails a concern for the possibility of uterine cancer. If you experience postmenopausal bleeding, please consult your doctor right away to be sure.


  1. Fitzpatrick LA, Pace C, Wiita B. Comparison of regimens containing oral micronized progesterone or medroxyprogesterone acetate on quality of life in postmenopausal women: a cross-sectional survey. J Women's Health Gen Med2000;9(4):381-7.