Thyroid disorders, particularly underactive thyroid, are extremely common, and most doctors treat them with a single medication. For hypothyroidism due to inadequate thyroid hormone production, they prescribe levothyroxine, also known as T4. You may recognize its brand names: Synthroid, Levothroid, Levoxyl. However, the active form of the hormone is T3, aka triiodothyronine or liothyronine. Some people find that taking T3 with T4 is more effective at making symptoms of hypothyroidism disappear.
Why Take T3 with T4?
Q. Hypothyroidism is rampant on one side of my family, and I was diagnosed two decades ago. After 15 years on either Synthroid or generic levothyroxine (adjusted to achieve a “normal” TSH), my internist agreed to let me supplement with T3 (liothyronine) in a compounded sustained release capsule.
We lowered the dose of levothyroxine (T4) moderately and I started taking a small amount of compounded T3 every 12 hours. It was like the sun came up! I have much more energy and all my typical hypothyroidism symptoms abated.
The only downside is that my insurance does not recognize the T3 therapy “because TSH was normal on T4 only!” My insurance carrier is obviously not outcome-oriented.
Patient Responses to Levothyroxine:
A. You are not the only patient who has been unhappy with levothyroxine (T4-only) treatment of hypothyroidism. A recent online survey of more than 12,000 individuals with hypothyroidism found that those taking levothyroxine alone were least satisfied with their results (Peterson et al, Thyroid, online April 5, 2018).
People taking a combination of T4 with T3, as you do, were better pleased with their treatment, while those taking desiccated thyroid extract, such as Armour, reported the fewest problems with weight control, fatigue, mood and memory. This natural pork extract contains both T3 and T4, though not in the same proportions as human thyroid glands.
The body converts T4 to the active hormone T3 by removing one molecule of iodine. But as many as 15 percent of hypothyroid patients are less efficient at this conversion (McAninch & Bianco, Annals of Internal Medicine, Jan. 5, 2016). They deserve treatment that includes T3 with T4 so that they can feel well. You can learn more about these controversies, interpretation of lab results and treatment options in our online Guide to Thyroid Hormones.
