Difference Between T3 and T4 Thyroid Hormone

OncoLink
Last Modified: August 14, 2012

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Question

What is the difference/what should I know about T3 and T4 thyroid hormone?

Answer

Kolin Hoff, MD, Endocrinologist at Penn Medicine responds:

Most people only need T4. A few people may be better if they also take T3. T3 is difficult to take because it only lasts a few hours in the body and if used needs to be taken at the same time every day and often several times daily.

This question and answer was part of OncoLink's Brown Bag Web Chat Series. View the entire transcript of Focus on Thyroid Cancer.