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Oxnard, CA
A 30-year-old female asked:

should t3 (liothyronine) and t4 levels be equal or is there a ratio between the two?

2 doctor answers2 doctors weighed in
Dr. David Geffner
Endocrinology 54 years experience
None: The thyroid produces mostly t4, very little t3 (liothyronine). T3 (liothyronine) is created in the nuclei of all your cells from T4 which it takes in. The ratio of T4 to T3 (liothyronine) actually circulating in the blood is quite high.
Dr. Su Fairchild
Integrative Medicine 24 years experience
Not quite: T4 is a storage (inactive) form of thyroid hormone that is converted to T3 (liothyronine) (active form) and reverse t3 (liothyronine). Think of T3 (liothyronine) as the gas and rt3 (liothyronine) as the brakes. The more important ratio is that of T3 (liothyronine) to reverse t3 (liothyronine). You want more gas than brakes.

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Last updated Jan 15, 2015
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