HRTs that are bioidentical
The term "bioidentical hormone" originally simply meant any hormonal agent that is identical in chemical structure to those produced by our own ovaries. That term says nothing about hormone balance or hrts; it only describes the molecular configuration.
When our body uses the hrts that contain bioidentical hormones, they are for the most part used as our own were: the metabolic processing steps are essentially the same. Why not exactly the same? Because no matter what the form of the hormone, the way in which it is delivered to the body does enter into the dynamics of the situation. When we have intact and functioning ovaries, we have only enough of our hormones in circulation at any given moment to meet our needs. This level is controlled by a number of different feedback mechanisms and in turn controls a number of other hormonal levels and other physical processes.
But when we have to obtain part of our supply from outside our bodies, we don't have any way to make that intake respond to our internal cues. Instead, the timing and form of the hrt we take builds its own dynamic, sometimes causing its own effects upon how the hormone can be used that are independent of the adequacy of the actual hormone amount averaged across, say, a 24-hour period.
One example of this would be that oral hrts, because of the intense burst of processing they need by the liver, can cause more gallstones/gallbladder attacks as well as elicit more of an inflammatory response, such that they are associated with a specific, non-hormonal set of effects. Another example would be oral progesterone use, which provides for a more neurologically active set of metabolites than when progesterone enters the body by other routes. So even though the hormone molecules themselves may be identical to our own, the route and delivery timing add their own contributions to the overall effect we see when we use them in hrts.
You'll note we don't use the term "bioidentical" on our website when we're discussing hrts. As we've noted elsewhere, we avoid using it because its original meaning has become conflated with a different meaning, pertaining to a specific marketing strategy. For clarity, then, we refer to hormones identical to our own in chemical structure as "human identical."
Bioidentical HRTs, the practice
The other use of "bioidentical" involves compounding pharmacies and the practice of physicians with whom they work. In carving out a new business niche for themselves in compounding hrts and advising women on them and selling test kits for hormone levels, they have chosen the term "bioidentical hormones" to describe this entire business practice. Fundamental to their marketing campaign is a philosophy expounded in the mid-90s by a few researchers at saliva testing labs, notably David Zava and Jonathan Wright, that women are best served by replacing not one form of the estrogen molecule, the active estradiol one, but a mix of the forms that mimic the blend found in a naturally menopaused woman.
This mixed-hormone concept was never really researched in a standard way other than to say look, when we test hormone levels in healthy women, this is what we find, refined by the sort of experiential "this seems to work for some women" work that we all, individually, do with hrts. There is no actual proven foundation for the premise that we best need a blend. We've written elsewhere about the three estrogens that have become the focus of this marketing approach.
What we think is most important about these three estrogens is that, speaking from the standpoint of physiology, they are not all individually necessary as original supplements. Our bodies have the innate ability to convert estrone and estradiol back and forth to meet our needs. Put in one form and, if it is human identical, it will be handled in the normal way to meet our needs, either as itself or as its other form. Estriol is a waste product, included in the belief that its limited range of effects is somehow safer in overall profile. In other words, it's filler, meant to extend the hrt effect without extending risk (although at therapeutic doses, it has been shown to not actually work out that way).
So do some women do better on this than straight-estradiol hrts? Absolutely. Some of us, for one quirk or another of individual metabolism, have trouble coping with some forms of estrogen efficiently. It may be a timing/delivery issue of plunking too much of one into our system at once; it may be an issue of not having enough of a cofactor/enzyme/whatever to carry out that much conversion at once. So yeah, there definitely is a place in the realm of hrt for blended estrogens and there are some women who do best on them.
But do all of us need the blends? Absolutely not. Some of us don't do those conversions back as well and need a straight dose of one or another estrogen to have enough to work with. And there's no way to predict this; there's no way to test for this other than to try hrts. There's a real role for blended hrts, just as there is a real role for multiple doses and routes of all hrts, but there is no single correct answer for all of us, however much anyone's marketing would prefer to convince us otherwise.
And this is where the marketed practice of compounding pharmacists lets us down: by suggesting that there is more uniformity of hrt response than we have actually found there to be. By insisting on selling a test and then claiming to tailor an initial hrt that will correct every single level abnormality at once, this distorts the actual physiological process and doesn't take into account the way that our bodies use all of these hormones interchangeably/interactingly.
Many of the hormone level alterations we see in surgical menopause, especially when we are starting hrt in the immediate post-hyst period, are responses to a sort of falling-dominos effect: one hormone loss kicks off another. So some of those levels represent a response to another imbalance, not a fundamental inability to balance that particular agent itself. In other words, if we correct one imbalance, many of the others will fall into line of their own accord and through our own innate processing capability. By throwing a whole shopping cart of hormones at us at once, based on a test that may or may not accurately reflect either our true resources or our true needs (more on testing's limitations), practitioners of this "kitchen sink" philosophy aren't giving our bodies the chance to use our own mechanisms to sort stuff out and are throwing further sources of instability and excess into the mix. In effect, they can be artificially holding us in an imbalanced, stressed state instead of providing the resources necessary to return to an unstressed, balanced state.
An alternative approach, that espoused by the American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for the Diagnosis and Treatment of Menopause (free signup required to read) takes a much more physiologically-justified direction in suggesting that we should deal with one hormone at a time in a descending order of priority. By alleviating, first, the priority estrogen need, we allow other hormones to ease back to their own innate levels, thus revealing whether or not we actually do have abnormalities in our ability to provide for them, as distinguished from abnormalities of supply due to borrowing from them to meet higher priority needs.
Compounding pharmacists make more money the more hormones we buy from them and the more times they have to test and readjust those hrt blends. It's a business model, not a primary health care delivery mode. And it's one that has been helped along by marketing in the publishing business, where celebrities further confuse this issue with their own books that promise all sorts of sexy wonders if we'll only buy into this or that program that they themselves are marketing.
Please don't get us wrong—there are many excellent and knowledgeable pharmacists, but diagnosis and treatment are not part of their professional preparation and certification. There are many good things that compounded hrts can do for us, like provide more flexible dosing or blends that may suit our own bodies needs better than retail options, but the industry of "bioidentical hrts" as it has come, in the marketing sense, to mean this test-and-kitchen-sink program, is not necessary for most women from a health/wellness standpoint.
And so our biggest concern is that as a result of the conflation of these two concepts, the pure biochemical definition of bioidentical and the marketing concept, women are in a sense deprived of an opportunity to fully understand their choices. There are many retail human-identical hrts, and yet current marketing (as well as the anti-hrt crusaders') efforts have made it seem as though the compounded combo hrts have as their only alternative Premarin. All prescription retail hrt is not Premarin, and yet that is the implication that many many women have been brought to believe. This is a deception and misconception that distresses us on behalf of all of the women who won't find their best choices because they don't know that more exists or they feel they cannot afford to use something "bioidentical" because the package the pharmacist is offering her is too expensive.
There is a place in the market for each and every hrt that exists today, as well as many that do not and that we can only dream about. There are women for whom the "kitchen sink" works the best; there are women for whom nothing but Premarin works. What we would prefer is that each woman be given a chance to find where on that continuum of choices she falls, not to feel that she has to choose between one end of it and the other because the rest is invisible to her thanks to marketing by pharmacies, drug reps, doctors, publishers, anti-hrt crusaders, insurance companies, and all of the others who seek to profit from her confusion and discomfort.