T3 Therapy May Be Substituted for T4 Therapy

Published: October 1, 2012

According to new research presented at the recent Endocrine Society's 90th Annual National Meeting, T3 (cytomel) can be substituted for Synthroid (T4) and be equally effective.

Marina Zemskova, MD, of the National Institutes of Health, in Bethesda, Md., presented the findings.

The researchers conducted a randomized, double blind, crossover study using a three times per day replacement regimen of T3 or T4. The target was thyroid stimulating hormone (TSH) between .5 and 1.5 following at least 30 days on a stable dose.

"The results suggest there is proof of the concept of effective therapeutic substitution of T3 for T4 therapy," Zemskova said during the presentation.

It would have been helpful if how the patients felt on each therapy also was considered significant, but perhaps that will have to wait for future research.


Zemskova M, Linderman JD, Babar NI, et al. OR11-3. Levothyroxine and liothyronine pharmacodynamic equivalence. A randomized, double blind, cross-over study. Presented at: The Endocrine Society's 90th Annual Meeting; June 15-18; San Francisco.

Jacob Teitelbaum, MD

is one of the world's leading integrative medical authorities on fibromyalgia and chronic fatigue. He is the lead author of eight research studies on their effective treatments, and has published numerous health & wellness books, including the bestseller on fibromyalgia From Fatigued to Fantastic! and The Fatigue and Fibromyalgia Solution. Dr. Teitelbaum is one of the most frequently quoted fibromyalgia experts in the world and appears often as a guest on news and talk shows nationwide including Good Morning America, The Dr. Oz Show, Oprah & Friends, CNN, and Fox News Health.

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