The pill vs. HRT
Oral contraceptives and hormone replacement therapy (HRT) both relieve symptoms caused by hormonal imbalance, including hot flashes, moodiness and vaginal dryness. But the two are not exactly the same, even though, points out Dr. Timothy Rowe, head of reproductive endocrinology and infertility at the University of British Columbia in Vancouver, "The line between the two is blurring so much that essentially they're two sides of the same coin."
Still, there is a difference, and it lies in the type of estrogen used. The pill and HRT both contain some form of estrogen and some form of progesterone. The pill contains a synthetic estrogen called ethinyl estradiol, which is used because of its strong ability to prevent ovulation. In theory, Rowe explains, you could use natural estrogen but you would need so much to inhibit ovulation that side-effects, such as nausea, breast tenderness and headaches, would be intolerable. The same is true of progestin. Natural progesterone itself could be used, but so much would be needed that the cost and the side-effects would be too great.
In HRT, on the other hand, the aim is to eliminate menopausal symptoms and recreate premenopausal hormone levels. Because pregnancy is no longer a possibility, virtually any estrogen and progesterone can be used. In North America, doctors tend to prescribe "natural" hormones - Premarin, an often-used brand of HRT, is derived from the estrogens in pregnant mares' urine - after menopause rather than synthetics because they are cheaper and doctors have decades of experience using them. The question nobody can really answer yet except by conjecture, according to Rowe, is why women should switch (though not all do) from the pill to HRT. "The reason we prefer to use what we use for HRT is mostly instinct," he says. "If you have ovarian failure - the ovaries have stopped producing estrogen and progesterone - the best thing to reduce symptoms is to replace the hormones the ovaries have stopped producing."
But that trend, he added, may be starting to change as both physicians and consumers express an increasing desire to use the same hormones postmenopausally as they did during the reproductive years. In addition, Rowe says there has been no evidence to show that natural estrogen is safer or more effective than synthetic estrogen. The latest HRT preparation to be introduced in Canada contains both a low dose of synthetic ethinyl estradiol and synthetic progestin, adds Rowe.
For the moment, doctors such as Dr. Christine Derzko, a reproductive endocrinologist at the Women's Health Centre of St. Michael's Hospital in Toronto, are encouraging women to stay on the pill until age 55 if they want to.
At that point they can either go off the pill or, if symptoms are still present and troublesome, onto a low dose of HRT. Derzko is noticing more women "quietly going back on hormones" following a big drop-off after the results of the Women's Health Initiative, a large study in the United States that was evaluating HRT use in postmenopausal women. "I think we all needed a good kick in the pants," she says. "We needed to stop and think what we were doing; we needed to look at lower doses." But, she adds, for a postmenopausal woman who exercises regularly and watches her weight, the benefits of hormone replacement can be excellent. "Healthy lifestyle is extremely important; you don't replace that by taking hormones," says Derzko. "But come on: all those good things over all those years could not be figments of people's imaginations."
