Hypothyroidism is a thyroid hormone deficiency, so it makes sense that our primary therapy involves ingesting either synthetic or animal-derived thyroid hormone.
There are 2 primary forms of thyroid hormone in the human body.
- T4 is the relatively inactive form, with only minor non-genomic activity. It converts to T3 or to Reverse T3.
- T3 is the only form of thyroid hormone we know to be active in the thyroid hormone receptor.
The limited Thyroid pharmaceutical market
Three thyroid hormone pharmaceuticals have been available on the market:
- Since the late 1800s: Animal-derived desiccated thyroid extract (DTE or NDT), which contains both T4 and T3 hormones
- Since 1949, Synthetic Levothyroxine (L-T4) which becomes T4 hormone in the body.
- Since 1953, Synthetic Liothyronine (L-T3) which becomes T3 hormone in the body.
However, Levothyroxine (L-T4) has taken over the thyroid medication market almost completely.
Patients are commonly offered only Levothyroxine (L-T4). It is offered under several brand names in Canada: Synthroid, Eltroxin, and Eutyhrox. Read more about “Why T4 monotherapy has dominated.”
Many doctors, and most thyroid patients, are unaware of the availability of two other options for therapy which contain the T3 hormone. Partly because of the small market for T3 hormone, competition is limited. Supply and pricing is largely controlled by the manufacturers.
- There is one Canadian supplier of Liothyronine (L-T3) sold as Cytomel. It is Pfizer.
- There is one Canadian supplier of dessicated thyroid (DTE / NDT) called Thyroid. It is ERFA Canada.
- Compounding pharmacies in Canada obtain raw Liothyronine powder from their chosen distributors.
Contrast with Diabetes medications
Diabetes is another widespread metabolic health condition.
Put access to thyroid medication in contrast with the openness of communication about a wide variety of diabetes medications and their availability on the market.
These medications are listed in Chapter 13 of the Diabetes Guidelines website in Canada:
Lispro U-200 Short-acting
Glargine U-100 (biosimilar)
Biphasic insulin aspart
Lispro/lispro protamine suspension
We also discuss the challenges of the Canadian thyroid therapy market in “Challenges: Therapy, part 2”