Consider the treatment of diabetes in contrast to the treatment of hypothyroidism today. Both are metabolic conditions and both are very sensitive to fine adjustments in hormone levels. We know that each patient is unique genetically, is at a different phase of disease, and that they may also have other health conditions in connection with their metabolic disorder.
For diabetes, a number of medication alternatives are available for doctors and patients to choose from. Guidelines in Chapter 13 of the guidelines.diabetes.ca website list all the different medication varieties in a complex table with a list of pros and cons and effects. In diabetes, the task of blood glucose measurement and insulin dosage is entrusted largely to the patient because of convenient devices that enable this.
Thyroid hormone medications
In contrast, official guidelines offer Canadian hypothyroid patients only offered one option: synthetic L-T4 monotherapy, better known in Canada by the brand names of Synthroid, Levothyroxine, Eltroxin, and Euthyrox. Although research is lacking on hypothyroidism in Canada specifically, most doctors patients appear to be unaware that there are alternative hormone treatments in existence.
Alternative thyroid therapies currently do exist for hypothyroidism, but they may become inaccessible if we do not protect our access to them.
- Synthetic T3 hormone, Liothyronine (L-T3) has been manufactured since the 1950s. [23, 24] The Canadian pharmaceutical market offers Cytomel, by Pfizer.
- Desiccated Thyroid Extract (DTE), also known to patients as Natural Desiccated Thyroid (NDT) is animal-sourced thyroid hormone. It has been used since the 1800s.  In Canada, we have Thyroid, by ERFA.
Both formulations are regulated by Health Canada and are available by prescription only.
Triiodothyronine (T3) is the most potent thyroid hormone that requires no further conversion to be activated, and therefore it is a potent tool for those who seem to lack T3 in blood and/or tissues despite L-T4 therapy.
The T3-based hormone therapies are underutilized by design. Awareness is not spreading due to medical leaders’ exaggerated fears about their safety and reliability, as well as fears of being disciplined by professional bodies. We believe this monopoly on T4 monotherapy is being promoted and staunchly defended by the medical system and pharmaceutical industry. Alberta’s medical practice guidelines have strongly discouraged the use of alternatives:
“Use L-Thyroxine for thyroid replacement. DO NOT use T3, T3/T4 combinations, or desiccated thyroid.” [15 (p3)]
The guidelines document gives no justification for its use of capital letters in this vehement restriction. Although it was revised in 2014, most of its eighteen references are sadly out of date, from the late 1990s to the early 2000s.
L-T4-T3 combination therapies
Despite the long history of use, medical professionals are currently debating the place of synthetic L-T3 medication in thyroid therapy. The most frequent approach is synthetic “T4/T3 combination therapy,” or simply called “combination therapy.”
Natural combination therapy, the use of desiccated thyroid extract (DTE), has rarely been studied scientifically since the synthetic pharmaceuticals attracted the attention of medical professionals. Although it has been the focus of two clinical studies, more rigorous research is being called for.[26, 27, 28]
Articles occasionally mention that some doctors and patients seem to be doing very well with combination therapy,  and some leading endocrinology researchers have opened their minds to it, stating that “it may be time to consider a personalized regimen of thyroid hormone replacement therapy in hypothyroid patients.” 
Medicine is now seeking to re-validate synthetic L-T3 through clinical trials and is approaching the topic with obvious reluctance and skepticism. Many researchers seem to approach the combination of the two synthetic hormones as if L-T3 were a new, revolutionary, experimental medicine, which is contrary to history. Although a form of thyroxine was synthesized in 1927, it was not useful in therapy until it was synthesized as a sodium salt “levothyroxine.” Desiccated thyroid remained the standard and preferred treatment until the mid-1970s. Synthetic L-T4 arrived to us around the same time as L-T3, around 1952.
Scientists sometimes treat patients’ “preference” for combination therapy with condescension, as likely only a placebo effect, and dangerously naïve, oblivious to risk. The research appears to dismiss the existing mountain of evidence: the wisdom and lore of patients and doctors who understand this hormone treatment modality through long experience.[33, 34, 35, 36] Knowledge from long-term clinical practice should be consulted as a starting point for rational inquiry, or science can waste labor on explaining the known, misunderstanding the basics, and splitting hairs over details of little consequence for health.
Therefore, the main barrier to its more widespread adoption is the current state of recent research and the dissemination of existing clinical knowledge. Thyroid “combination therapy” studies are so varied in their methods that it is widely acknowledged they are too difficult to synthesize. Indeed, when combining two hormones there are many different combinations possible, in addition to many research designs. Several of the studies have dosed the T3 hormone inappropriately; they also seem to be oblivious to its interrelationship with circadian rhythms and adrenal and sex hormones that are amply discussed in patient resources. Many have restricted these treatments’ T3 dosage by various theories about a “natural” T3/T4 hormone ratio. They also do not seem to understand or accept the unique response of TRH and TSH hormones to the oral dosing of T3, which is a major limitation to any study of “benefit” (see our rationale). Nevertheless, this important research must continue.
To the skeptics and those who are resistant to change, there may never be enough evidence to convince. The hypothetical and unproven risks of these earlier hormone therapies will loom larger than the history of their safe and effective use. Any reports untoward incidents with T3-based therapies will likely be inflated beyond reason. Meanwhile, doctors will continue to make mistakes with L-T4 therapy, some being seemingly unaware of the contents of the product monograph. For some researchers and doctors, patient symptoms are an annoying distraction rather than a signal of a problem with the therapeutic approach; it will always be tempting to blame health issues on any treatment modality as “unrelated to thyroid function.” 
Next section: Challenges: Therapy, Part 2
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