FRIDAY, May 4 (HealthScout) -- For older women who can't or don't want to use synthetic hormone treatments, the news is good: Natural progesterone cream works as part of hormone therapy for the post-menopausal years.
Using the cream balances the effects of estrogen on the uterus, keeping the lining from becoming too thick -- a problem that can become the forerunner to
uterine cancer, says a study presented this week at the annual meeting of the American College of Obstetrics and Gynecology.
"I've always believed that it would work, and now this is our second study to show that natural progesterone cream does work. It has created miracles," says study author Dr. B.H. Leonetti, an obstetrician/gynecologist at St. Luke's Hospital Center in Bethlehem, Pa., where the research was conducted.
Miracles not withstanding, not everyone shares the excitement.
"Based on this available information, I don't think women can begin to use progesterone creams instead of the tried-and-proven methodologies for conferring endometrial protection. There is not enough data here to abandon what's been safe for quite a period of time," says Dr. Steven Goldstein, professor of obstetrics and gynecology at New York University School of Medicine.
Progesterone is a female hormone made by the ovaries during the second half of each menstrual cycle. As a woman ages, her levels of both progesterone and estrogen decline sharply, inviting a host of symptoms, including hot flashes, insomnia, mood swings and fatigue.
Estrogen therapy can help, but if given without progesterone, the risks increase for uterine and breast cancer. For many women the answer has been synthetic progesterone paired with estrogen, a combination commonly used in hormone replacement therapies today. But the side effects can be a big drawback.
"I call synthetic progesterone the Drug Women Love To Hate. It causes bloating and breast tenderness and moodiness and PMS, and it winds up that it's not good for your lipid profile either. And it's certainly not protective on the breast," says Leonetti.
While several forms of natural progesterone have been developed -- most notably an oral version called Promethium, and a vaginal gel called Crinone -- Leonetti says concentrations are too high, and they still produce way too many side effects.
She says a quarter teaspoon of natural progesterone cream used daily can give a woman the same amount of progesterone that's made normally by the ovaries during a menstrual cycle.
Goldstein says the theory may sound good, but there is no convincing evidence that the small amount of progesterone absorbed through the skin can do what the higher doses of other natural forms of progesterone have been proven to do.
"It will be interesting to see in a long-term study if the transdermal progesterone has less of the typical progesterone side effects that you get with oral [natural] progesterone, and still accomplishes the same goals, long term," says Goldstein.
The study was small -- just 58 women, average age 55, each treated within six years of completing menopause.
Each woman had the lining of her uterus measured for thickness three times: once in the beginning of the study, once after two weeks of taking estrogen-only therapy, and the last time after four weeks of rubbing on either a placebo cream or two natural progesterone creams of varying strengths.
The result showed the uterine linings of women who used the progesterone cream did not continue to thicken while the linings of the women who used the placebo cream did, just as they would have if they had been given estrogen-only therapy.
Whether women would get the same results with either synthetic progesterone or other forms of prescription natural progesterone, the authors could not say. However, Leonetti says studies are planned for head-to-head comparisons of the various types of progesterone.
The study was funded by a company that makes natural progesterone cream. However, independent laboratories were used to analyze the biopsy samples.
What To Do
Don't change your hormone regimens yet.
"It didn't not work, so in that sense it's worthy of further study. But this study is in no way, shape or form of the kind of quality or duration or size where you could suggest to any woman that she could abandon traditional, tried and true progesterone treatments based on what we have learned thus far," says Goldstein.
For women trying natural progesterone therapy, the study's author warns against buying products touted as "hormone precursors" that are converted by the body into natural progesterone.
"This does not work. The conversion has to take place in the laboratory from substances taken from either wild yams or soybeans, It does not occur in the body, and using these products won't help you," says Leonetti. To get enough progesterone for therapeutic value directly from the source, one would have to eat "a ton of wild yams or soybeans," says Leonetti.
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