Mimicry: The idol of T3-T4 combo therapy 2004-2014

They say that history is written by the victors. Not always. Sometimes histories are written by advocates for the oppressed and disenfranchised. A common theme on our website is the need to see current practices and thyroid therapy challenges in light of thyroid therapy history. Instead of trusting histories written by scientists, one ought to go to the primary sources to reconstruct that history. This article connects several key works to examine the history of synthetic T3-T4 combination therapy since the 1990s. In part 1 of this series, “The foundations of synthetic T3-T4 therapy in the 1990s,” I examined Escobar-Morreale’s …

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The foundations of synthetic T3-T4 therapy in the 1990s

A trend in thyroid therapy, sparked by a 1995 rat study, attempted to mimic a narrowly estimated T3:T4 ratio secreted by human thyroid glands. This trend was based on a theory of pharmaceutical mimicry of “the” thyroid gland. Its proponents chose to represent every human being’s thyroid gland by the narrow statistical average secretion ratio of 14 people’s thyroid glands estimated in a classic study by Pilo and colleagues in 1990. In my recent post, I introduced you to Pilo’s Subject #7, the only man in the study whose thyroidal secretion ratio was close to Pilo’s estimated average among nine …

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Free T3 peaks and valleys in T3 and NDT therapy

Lack of knowledge about Free T3 peaks and valleys contributes to failure and frustration in T3-based therapies, including desiccated thyroid and T3-T4 combination therapy. On patient support groups, I often see conversations that go like this: Another common patient exchange usually goes like this: So many times, I’ve thought to myself, “I really wish all doctors who prescribe T3 or NDT medication understood the science behind the T3 dosing effect.” In fact, even thyroid patients taking T3 or NDT should know the Free T3 dosing curve because it strongly influences their symptoms and lab results. Yes, you might be hypothyroid …

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Stop spreading the unscientific myth about the normal T4:T3 ratio!

Sigh. Just sigh. Even some of our best thyroid patient advocates can unknowingly share misinformation about thyroid therapy. Mary Shomon’s thyroid articles on Verywell.com are usually to be trusted. But yesterday I was saddened to see that an article supposedly authored by Mary Shomon was spreading unscientific myths about “normal” thyroid secretion ratios being 13:1 to 16:1. These statements are misleading. They are not truly representative of the wide range of ratios of thyroid hormone in health, according to science. These 13:1 or 16:1 ratios have NEVER been clinically proven to be the only safe and effective ratios in thyroid …

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How to calculate LT3 vs. LT4 substitution: New thyroid science

What does NEW thyroid science have to say on the topic of thyroid pharmaceutical equivalency? How many micrograms of L-T3 Liothyronine (i.e. Cytomel) are equivalent to L-T4 Levothyroxine (i.e. Synthroid)? Thyroid hormone pharmaceutical monographs currently provide very rigid and low-ratio equivalency statements: In my previous post, I uncovered the historical origins of this low 25:100 mcg ratio in the product monographs. I showed that five authoritative publications promoted a higher average of 25 to 35 mcg L-T3 per 100-mcg L-T4. In this post, I will first review a set of groundbreaking articles from 2010-2013 that discussed this very issue of …

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