Thyroid Hormones
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A complete pathway map of T4 and T3 metabolism and clearance
Biochemical pathway maps are an important aspect of medical education and medical problem-solving. They help us to view a network or series of chemical reactions in cells. In this article, I present a comprehensive science-based pathway map showing all the major pathways of both T4 and T3 hormone metabolism, also including their urinary clearance. I…
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The leaky buckets analogy of thyroid hormone metabolism
Thyroid hormone metabolism is a very complicated system. A visual analogy sometimes goes a long way to assist comprehension. Throughout the body, there are at least six major pathways for T4 transformation or excretion, and at least six major pathways for T3 transformation or excretion. In the visual, the fluid represents circulating thyroid hormone concentrations.…
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Focusing on T3: The T3 hormone or the LT3 pharmaceutical?
Who needs “T3”? We received a friendly and well-intended comment lately. It illustrated that in today’s Global English, we sometimes have a hard time defining and understanding what “T3” means when a person is talking about T3. Are they talking about T3 the hormone, or T3 the pharmaceutical? “I like your content in general, but I’d…
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Winter T3 loss: Why it matters to thyroid patients
It’s April. You’re a thyroid-hormone treated person with a thyroid disability on a fixed budget of thyroid hormone. Have you been feeling hypothyroid in the past few months? If so, you’re not alone. If not, thank your thyroid, or your thyroid doctor. Scientific studies show a winter-season loss of Total or Free T3 (FT3) in…
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Ingbar and Braverman’s historic study of LT4 monotherapy
As part of my post on “The thyroid gland is a T3 shield,” I reviewed a research article by Ingbar and team from 1982. Wow. What a treasure. The title of this article is “Elevated serum thyroxine concentration in patients receiving ‘replacement’ doses of levothyroxine.” Just look at that title. They began their title with…