Thyroid UK
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Help with interpreting reverse T3

I have received my Free T3 and Reverse T3 and would appreciate some help in understanding the ratio.

Free T3 5.8 (3.1 - 6.8 pmo1/L)

Reverse T3 27.9 (9 -35 ng/dl)

Using this calculator: (Stop the Thyroid calculator did not have the conversion I needed)

My result came back as 0.013516599782802224

What does this mean? I have read 2 is meant to be a healthy ratio?

Any suggestions?

Thank you

6 Replies

Sorry I can't help you but thinking of having the same test. How/where did you get yours done?


I see a doctor who practises functional medicine. My bloods were sent to "The Doctors Laboratory" but I think Genova would run this test


Thanks Nik07


The STTM book gives this advice:

1. If both RT3 and Free T3 are in pmol/L or pg/mL, multiply the free T3 by 1000, divide the Free T3 by the RT3.

2. If theRT3 is nmol/L and Free T3 is pmol/L, divide the Free T3 by the RT3.

3. If the RT3 is ng/dL and Free T3 is pg/dL, divide the Free T3 by the RT3.

4. If the RT3 is pg/mL and Free T3 is pg/dL, multiply the Free T3 by 100, then divide Free T3 by RT3.



Thanks Hypoteq, it seems that the measurements used by the lab do not feature in the STTM which is most frustrating.


You can get a conversion calculator for just about anything at

or just type the conversion you want into a search engine and it'll take you there


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