Synthetic bioidentical hormones.

That may sound like an oxymoron, but more precisely describes the way we get and use bioidentical hormones.

Please don't take offense, especially if you're a provider who subscribes to my emails and YouTube videos. But I may say some things that go against everything you’ve been taught. I may even say some things in this post and video that are the exact opposite of what you’ve believed.

Feel free to disagree with me. Your comments and feedback encourage me. I’ll try and see things from your perspective.

Natural, Synthetic, Bioidentical

Our friend, Dave pastored a church, writes books and blogs, studied theology, and taught New Testament at Calvin University in Grand Rapids, MI. A man of words, he wrote and taught in Greek, Hebrew, Aramaic, German, and of course, English.

He used to say, “Words don’t have meanings . . . they have uses.” What he meant was that words are defined by the way we use them in common language.


Merriam-Webster defines "natural" as “existing in or produced by nature: not artificial.”

The etymology website, Etymonline says that “nature” was first used in the 14th century in the context of . . . "not artificially cultivated or created, existing in nature


Etymonline also shows the original use of the word “synthetic” . . . “From 1874 in reference to products or materials made artificially by chemical synthesis; hence ‘artificial.’”


Although the word bioidentical appears in no etymology books or sites, it comes from the word “identical,” which, according to etymonline, “Replaced Middle English idemptical (late 15c.), from Medieval Latin idemptitas "identity," from Latin idem.”

Bioidentical first showed up in PubMed, an online database of scientific and medical studies, around 2001. CR Walker wrote the first use of “bioidentical” (in the context of hormones) in an article in Advanced Nurse Practitioner entitled, Bioidentical hormone replacement therapy. A natural option for perimenopause and beyond.

Bioidentical hormones describes hormones that are exactly the same in chemical structure as hormones produced by the human body.

Synthetic vs. Bioidentical: A False Dichotomy

Unfortunately, many of us in the hormone optimization world have created a false dichotomy. We speak and write about hormones in a way that suggests there are only 2 options:

  • Synthetic Hormones
  • Bioidentical Hormones

This assumes that synthetic and bioidentical are mutually exclusive terms. We further confuse patients by applying the word natural to bioidentical hormones, making patients believe that natural and bioidentical mean the same thing.

Imprecise Language

In my research on hormones and hormone optimization, I find almost no one who is using the terms natural, synthetic, and bioidentical precisely. I hear hundreds or even thousands of patients and providers who use these terms in ways that only add to the confusion.

A hormone cannot, by definition, be both natural and synthetic at the same time. It comes either from nature (natural) or is man-made through a chemical synthesis process.

Premarin® Is Not Synthetic

Premarin® , also called conjugated equine estrogens, comes from the urine of pregnant mares. You may know that Premarin® came on the menopause scene in 1943 as a treatment for hot flashes and other menopause symptoms. Prescriptions for Premarin®, one of the most-prescribed medications in 2001, dropped dramatically after the results of the Women’s Health Initiative seemed to suggest that the drug increased breast cancer risk.

Since the WHI, doctors, patients, health educators, and others have often called Premarin®  a synthetic hormone.

If we look back at the uses of the words natural and synthetic, we can easily recognize that Premarin® doesn’t fit the word synthetic.

The ingredients in Premarin®  do not come from a chemical synthesis process, they come from horses. Premarin® is produced by natural means, collecting [natural] urine from a [natural] horse. It’s not at all synthetic.

Several years ago, I cut a Premarin® tablet in half. I took the 2 halves of the tablet and smelled them. They reeked very strongly of horse urine.

If horse urine is not natural, I don’t know what is. I suspect that’s why Pfizer®, the manufacturer, coats Premarin® tablets with sugar, to mask the natural (but awful) scent.

ALL Bioidentical Hormones ARE Synthetic

Over the past 20 years or so, healthcare providers have started referring to bioidentical hormones - hormones given to humans to replace hormones their bodies need, but don’t make any more :

  • estradiol
  • estrone
  • estriol
  • levothyroxine
  • liothyronine
  • progesterone
  • testosterone
  • DHEA
  • pregnenolone

I don’t have a problem with these hormones being referred to as bioidentical.

Bioidentical hormones describes the fact that estradiol, testosterone, progesterone, and the others on the list have chemical structures that are exactly the same as their hormone counterparts produced by the human body.

What concerns me is the misunderstanding of where, specifically, these hormones come from.

Every one of these bioidentical hormones comes from a chemical synthesis process.

They are all synthetic. And they are all bioidentical at the same time.

That’s where the false dichotomy comes in.

The phrase “bioidentical vs. synthetic hormones” is both confusing and untrue. The reality about bioidentical and synthetic hormones is that there is no clear distinction between them - they can and do overlap.

Not All Synthetic Hormones Are Bioidentical

A long list of hormones given for menopause and other hormone-related issues are synthetically produced, but not chemically identical to human hormones.

Synthetic Bioidentical Hormone Becomes Non-Bioidentical


Medroxyprogesterone adds a slight adjustment (a medroxy group) to the chemical structure of progesterone that makes it much more powerful than progesterone. That just means it takes a much smaller dose of medroxyprogesterone (5-10MG) to accomplish some of the activity of progesterone (which might require 100-200MG).

The results of the Women’s Health initiative and the Epic-E3N Cohort study indicate that the slight chemical change in medroxyprogesterone has profound implications for its safety profile. Women given medroxyprogesterone have higher risks for breast cancer and blood clots than women taking bioidentical progesterone.


  • Not Natural
  • Synthetic
  • Not bioidentical
Synthetic Bioidentical estradiol Becomes Ethinyl Estradiol

Ethinyl Estradiol

Ethinyl estradiol adds a small adjustment (an ethinyl group) to the chemical structure of estradiol. This small adjustment makes ethinyl estradiol more potent than estradiol. It also allows ethinyl estradiol to be used as an oral contraceptive.

Ethinyl estradiol

  • Not Natural
  • Synthetic
  • Not bioidentical

Most Natural Hormones Are Not Bioidentical

Several hormones that are used to treat hormone deficiencies in humans can be considered natural. Derived directly from natural sources, they don't come from a chemical synthesis process.

Premarin®, as I’ve already mentioned, is the hormone that often gets referred to as synthetic when the reality is that it’s natural.


  • Natural
  • Synthetic
  • Not bioidentical
Premarin® Advertisement - Not Bioidentical or Synthetic

Magazine Advertisement for Premarin® Conjugated Equine Estrogens

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Armour® Thyroid - Not Synthetic, Not Bioidentical

Armour® Thyroid - Contains Levothyroxine (T4) and Liothyronine (T3) from Pork Thyroid Glands

Thyroid products derived from pork include the thyroid hormones levothyroxine (T4) and liothyronine (T3). Armour® Thyroid, along with NP® Thyroid, Westhroid®, and others are made by desiccating (drying) pig thyroid glands. Manufacturers grind desiccated thyroid glands into a fine powder and mix them with other ingredients to form a solid oral tablet. Each 1 grain Armour® Thyroid tablet is calibrated to contain 38mcg of T4 and 9mcg of T3.

These naturally-derived hormones cannot be considered bioidentical because they are contaminated with multiple ingredients (pig hormones) not found in humans.

Armour® Thyroid, NP®, Westhroid®, etc.

  • Natural
  • Synthetic
  • Not bioidentical
Nuns Urine - Contains Non Synthetic Bioidentical Hormones

Natural Hormones That May Be Bioidentical?

Pergonal® and Menopur® are both natural hormones. Used for infertility since the early 1960s, they’ve fallen out of favor and aren’t as available as they once were.

When they were available, they contained a mixture of hormones that include FSH (follicle stimulating hormone) and LH (luteinizing hormone), which are derived from the urine of post-menopausal women. Urine was mostly collected from Roman Catholic nuns, with the express permission of the pope. Nuns’ urine is a completely natural source for these drugs. The urine of nuns was specifically used because of the low likelihood any of them would be pregnant, which could drastically change its hormone content.

It’s debatable, but these two hormones might also be considered “bioidentical,” since any contaminants in them would be human hormones or metabolites of human hormones.

Pergonal®, Menopur®

  • Natural
  • Synthetic
  • Bioidentical

Bioidentical AND Synthetic Hormones

I contend that the hormones that are safest, most effective, and most useful are both bioidentical - exactly the same chemical structure as human hormones - and synthetic - derived through a chemical synthesis process.

The bioidentical part makes hormones function exactly the same as their human counterparts. Bioidentical progesterone functions the same as human progesterone in breast tissue, uterine tissue, the brain, and in other tissues.

The synthetic part means that these hormones won’t be contaminated by a bunch of other ingredients that come from animal or human urine or thyroid glands. Synthetic estradiol, for example, is much easier to make into a purified form that is 100% estradiol.

OK, so maybe it’s only 99.6% estradiol and it has a tiny amount of contaminants. But that’s certainly preferable to naturally derived hormones with massive amounts of contamination.

Bioidentical Hormones From Yams?

Do you know where bioidentical hormones come from? Many people, including patients and healthcare practitioners, believe that hormones come from yams. Penn State chemistry professor, Russell Marker and his fascinating chemical synthesis story has completely transformed not only the way we obtain hormones but also the cost of those hormones.

Stay tuned!

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About the Author

With over 26 years of experience as a licensed pharmacist in Utah and Colorado, I specialize in hormone optimization and menopause management. I hold certifications in Advanced Bioidentical Hormone Replacement Therapy (ABHRT) from Worldlink Medical, C4 Hormone Replacement Therapy from the Professional Compounding Centers of America and the American Academy of Anti-Aging Medicine, and I am a Brain Health Coach certified by Amen Clinics.

I also share my expertise on my Simple Hormones YouTube channel where my videos have been viewed over 950,000 times and over 18,000 viewers have subscribed.

  • Hey. I speak and talk about this issue. The issue with these words/phrases is what people WANT to hear and what the internet will allow passing along and viewing specific information (SEO). It always grated my brain to hear “natural/bio-identical/synthetic” in the context of hormones but worse, having to perpetuate it on websites and talks. Your video took about 10 to 15 minutes just to explain this issue. A 45 to 50-minute lecture on hormones, that is a lot of time to use up. In my hormone courses I spend 1 hour talking about just those definitions. To my patients in front of me I simply boil it down to this: “I am choosing what I feel is the right hormone for you that your body will accept and minimize any harm. I want your body to respond in the most positive a “natural” way to the hormone maximizing the benefits all while minimizing issues both short term and long term.” Most patients will respond to that…….Like you, it drives me NUTS when I hear these terms mixed and misused…..

    • Great insights! I don’t know that we can change the entrenched terms and ideas . . . but at least we can attempt to untangle some of the confusion patients experience because the language has been used imprecisely.

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