Thyroid pharma: Bioidentical yet harmful?

Thyroid hormone pharma-Denies-biology

Any fair criticism of a medication’s potential for harm or benefit should first examine the properties of the medication and how it interacts with the human body in general.

Next, we should distinguish the content of a pharmaceutical tool from its use (dosing adjustments, circumstances).

Then finally, we should consider this: The therapy has to fit the patient’s individual biological needs and responses, rather than a pre-set model of perfection forced on them by the doctor.


One fundamental biological fact unites all thyroid hormone pharmaceuticals: A pill containing thyroid hormones will never, ever be a gland.

Only living thyroid tissue is truly bioidentical and adaptable and part of the complete hypothalamus, pituitary, thyroid (HPT) axis. Expecting pills to function exactly the same way as a thyroid in the HPT axis is ridiculous perfectionism. Thyroid patients on therapy are still disabled. Taking hormones orally does not magically fix us or totally heal us. Forcing us to fit into the model of the hormone secretions and responses of the healthy-thyroid human being has to be reconsidered.

Even the artificial method of hormone delivery, orally and through GI tract, makes a difference. We each have a different GI tract and these hormones interact with this complex environment on their way to the bloodstream. How is that like a thyroid secreting hormones? It’s not.

Also, the fact that thyroid therapy tends to be a static daily dose, not a changeable dose, can itself be a significant difference and affect our bodies differently over time.


The next basic feature that unites the all thyroid pharmaceuticals is that they all provide “bioidentical” hormones.

“Bioidentical” means that after they are absorbed and taken up into our bloodstream, they yield T4 or T3 hormones that are virtually identical in molecular structure to the hormones that we humans secrete from the thyroid gland.

These molecules also function in the same way as our own hormones would. After they enter blood, the T4 and T3 also get metabolized into all the other forms of thyroid hormone: RT3, two types of T2, and T1. This is naturally part of the body’s use and recycling of iodine. (1a)

(NOTE: To explain the Levo- and Lio- prefixes, Levothyroxine (L-T4) and liothyronine (L-T3) are synthetic forms of human-secreted thyroid hormone molecules. Human-secreted thyroxine and triiodothyronine are also both “levo-isomers,” which means that they have a certain degree of counter-clockwise rotation between two rings in the molecule. (1b) Thyroid scientists have experimented with a wide range of possible molecular structures and rotations. They have found this particular shape to be the one the body naturally secretes, recognizes, prefers, and readily uses. (2) )

They are UNlike other types of pharmaceuticals that are chemicals the human body sees as foreign.

Because they are bioidentical, all thyroid hormone medications are far more likely to be benign than harmful … as long as we use them to provide what our body needs.


Overall, the differences between 1) synthetic, 2) animal-derived, and 3) our own hormones is that 1) the synthetics are bound to sodium (salt) that dissolves during transport through the GI tract, while 2) desiccated thyroid comes along with some of the proteins found in a porcine thyroid gland (thyroglobulin), and 3) our own gland secretes T3 and T4 directly into the bloodstream.

Another difference enables several companies to market different brands of T4, T3, and dessicated thyroid: they can have different inert ingredients (binders, colors) and very minor differences in manufacturing.

These fillers can influence how well the hormones are absorbed in the GI tract, which might mean one brand of synthetic T3 may give you a little more T3 in bloodstream than another. Their inactive ingredients might also cause an allergic reaction.

As for animal-derived hormone, two different brands of desiccated thyroid might have slightly different number of micrograms of T4 and T3 in them, yielding a very minor difference in T3:T4 ratio and amount. — But that’s different from saying you can’t trust one batch of the same brand of desiccated thyroid to be the same as the other. That’s no longer a problem in our modern day and age.

Every thyroid patient and doctor has to keep these differences in mind. They should realize that if one medication doesn’t work that well, there are other options … one could change between two brands of synthetic hormone, or switch between two brands of desiccated thyroid, or try any combination.

Anything can change the body’s response slightly, for better or worse. You can’t know until you try.

For all these reasons, it’s better to have diverse options available and permissible, rather than only have one type of pharmaceutical alone while the others get forbidden and go on shortage and get too costly.

But that’s what pharma prejudice does. It takes away options, and in doing so it can ruin lives.


In 2014, two American endocrinologists, Biondi and Wartofsky, tried to use an old clinical study as ammunition to attack desiccated thyroid (reviewed earlier on our blog Penny & Frasier, 1980). (3, 4)

All of these researchers tried to blame desiccated thyroid for causing potential harm, when the imagined harm was largely in their interpretation of the data.

Penny & Frasier’s 1980 study showed that a group of young children taking desiccated thyroid almost all had high T3 levels above reference range.

They reasoned incorrectly from this that desiccated thyroid pharmaceuticals tend to “cause” supraphysiological levels of T3 hormone and that the children were all in imminent danger of hyperthyroidism. However, the children were completely healthy and had normal growth rates and weights for their age, they had no clinical signs of hyperthyroidism, and they had been maintained for many years at the same dose. They had a normal TSH and lower-range T4 to counterbalance their higher T3. They needed to have less T4 to add T4-T3 conversion because they already had abundant T3 in bloodstream.

The researchers didn’t say, but the children could have been dosed once daily and their blood drawn when T3 was at its highest peak during the day, within 2-4 hours post dose. Who knows how low their T3 levels would have been prior to a daily dose, or at their average, 12 hours after a dose. To even out peaks and troughs in T3, the children could have had their dose divided and taken two or three times a day.

Many of the researchers’ presumptions were suspect, as were their fearful conclusions against desiccated thyroid pharmaceuticals.

Instead of reducing the children’s dose or changing dose timing and seeing whether the children improved or worsened and how it changed lab results, they chose to switch them to levothyroxine, their favored therapy. It wasn’t a fair trial of desiccated.

The change of thyroid pharmaeutical did what it was expected to do.

It flipped their T3:T4 ratio.

It drastically lowered their T3 by means of T4 domination.

Penny & Frasier’s prejudice against desiccated thyroid was based on a reference range boundary derived mathematically from a model of health, based on people with naturally derived T3:T4 hormone ratios and a healthy gland.

Their fear and prejudice had nothing to do with the nature of the pharmaceutical. It was obviously bioidentical and potent, and it had obviously been effective in maintaining health and growth. They simply did not prefer the T3:T4 ratios and T3 levels it yielded in these particular people’s blood because it looked unnatural. But what they did was equally unnatural.

We’ll never know what happened after that study. As the children continued to grow up, hopefully their doses would have been adjusted appropriately. Perhaps some children suffered terribly and begged to go back to desiccated thyroid while others were healthy on levothyroxine.

One thing is for certain, the researchers benefited.

They took advantage of this opportunity to promote their preferred medication and denigrate another. They got the career credit and fame of authoring a journal article. The researchers seemed to think they were heroic.

Other articles showing benefits of desiccated thyroid moulder away in archives because they are not randomized clinical trials, but this flawed study from 1980 was resurrected to continue the decades-long battle against desiccated thyroid pharmaceuticals. Double standard.


All thyroid therapies are artificial, all types yield bioidentical hormones, but not every brand or type affects an individual the same way. Therapy needs to fit the patient’s unique disability and unique biology.

Science says the T4 molecules you will get out of a brand of desiccated thyroid are not any better or worse than the T4 molecules you get from a brand of levothyroxine or you get from your thyroid. There is no intrinsic “danger” of either animal-derived thyroid hormone or synthetic.

A pharmaceutical will always be an adaptation, a prosthesis, like a wooden leg or a wheelchair.

You can’t blame a pharmaceutical tool for not imitating nature perfectly. Any single one of them may contain an unnatural ratio and may create an unexpectedly distorted ratio in blood. Even T4 monotherapy distorts hormone ratios and levels.

Just as hormone meds can distort hormone levels and ratios, wheelchairs don’t all fit through normal-width doors. Accommodate the prosthesis and the patient.

You can’t blame the pharmaceutical tool for the way someone uses it or how someone’s body responds to it. It’s like saying a hammer is always worse than a screwdriver, when they are both hand tools. Both can be beneficial and useful in making a customized cabinet fit a kitchen.

What causes harm? Forcing.

If you force the “right” med on the wrong patient, that harms them. If you misinterpret a medication that is working well as harmful, taking it away harms them.

Other illnesses get a range of therapies that accommodate to each person’s unique physical disability. But you can’t really see our disability and you can’t experience it every day. Every thyroid patient is unique. Thyroid therapy can’t normalize us by normalizing lab numbers alone.

We need ALL tools at hand to build a therapy that fits the patient.

  • Tania S. Smith


1a) Chatzitomaris, A., Hoermann, R., Midgley, J. E., Hering, S., Urban, A., Dietrich, B., … Dietrich, J. W. (2017). Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming. Frontiers in Endocrinology, 8.

1b) Young, W. F., Gorman, C. A., Jiang, N. S., Machacek, D., & Hay, I. D. (1984). l-Thyroxine contamination of pharmaceutical d-thyroxine: probable cause of therapeutic effect. Clinical Pharmacology and Therapeutics, 36(6), 781–787. Retrieved from

2) Camerman, N., & Camerman, A. (1972). Three-Dimensional Structure of L-Thyroxin. Proceedings of the National Academy of Sciences of the United States of America, 69(8), 2130–2131. Retrieved from

3) Biondi, B., & Wartofsky, L. (2014). Treatment with thyroid hormone. Endocrine Reviews, 35(3), 433. 10.1210/er.2013-1083

4) Penny, R., & Frasier, S. D. (1980). Elevated serum concentrations of triiodothyronine in hypothyroid patients. Values for patients receiving USP thyroid. American Journal of Diseases of Children (1960), 134(1), 16–18.

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