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Thyroid UK
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RT3 results - help please

I have had Hashi’s for the past 20 years and a couple of years ago I became the victim of adrenal fatigue and have been working hard to rectify this. I recently had the Thyroid Check Plus RT3 test done and would appreciate some help in analysing the figures. I was under the impression that an RT3 ratio of 20 is what we are aiming at. Mine at 15.3 seems to be in range, is this figure good or bad?? Results below:

TSH 3.06 (0.27 - 4.20)

T4 15.8 (12 - 22)

Total T4 86.6 (59 - 154)

T3 4.23 (3.10 - 6.80)

RT3 18 (10 - 24)

RT3 ratio 15.3 (15.01 - 75)

Thyroglobulin antibody 669.000 (0 - 115)

Thyr Peroxidase antibodies 353 (0 - 34)

6 Replies

You're under medicated to have TSH so high

Dose should be increased by 25mcgs steps until TSH is around one and FT4 towards top of range and FT3 at least half way in range

Have you had vitamin levels tested recently?

Are you on strictly gluten free diet?

Bloods retested 6-8 weeks after each dose increase

All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results


Thanks SlowDragon. These results are the latest since massive general improvement since seeing a Functional Doctor, going gluten free, taking Vitamins, Minerals and others for adrenal support. I feel I have done everything I can to get back on track.

I’m seeing my GP soon and would like to be able to explain about my improvement, particularly about the RT3.

I really want to know whether an RT3 ratio of 15.3 is acceptable.


You cannot just take an rT3 ratio in isolation and make it mean anything. It doesn't mean much at all, and I have yet to work out quite why they even bother to work it out!

What is important is your FT4 and your FT3. And, whilst you are obviously under-medicated, because both of them are just under mid-range, the comparison is pretty good. You seem to have reasonable conversion, and that is what counts. So, your rT3 is ok because you don't have lots of unconverted T4 sloshing around. But your ratio is low because your FT3 is low. And all that can be deduced by looking at your FT4 and FT3. In my opinion, the rT3 test is just a waste of money.

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As has been written elsewhere, the T3:RT3 is nonsense maths, an equation giving an appearance of credibility, even though it makes no sense. If a low ratio can be from both high or low Free T3, then the ratio is useless, because it can mean two different things; this makes it mathematically invalid. BMI is an example of a valid ratio where weight is divided by height, and the higher the BMI ratio, the more overweight the person. A high BMI ratio does not mean overweight in some cases, but underweight in others. Whereas using the T3:RT3, a low rT3 ratio can mean both too much OR too little T3.

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rT3 ratio is fine.


If you are taking Levothyroxine you are undermedicated and should request a dose increase.

The goal of Levothyroxine is to restore the patient to euthyroid status. For most patients that will be when TSH is 0.3 - 1.0 with FT4 in the upper range. FT4 needs to be in the upper range in order that sufficient T3 is converted. Read Treatment Options in thyroiduk.org.uk/tuk/about_... Email dionne.fulcher@thyroiduk.org if you would like a copy of the Pulse article to show your GP.

Thyroid peroxidase antibodies are positive for autoimmune thyroid disease (Hashimoto's). There is no cure for Hashimoto's which causes 90% of hypothyroidism. Levothyroxine treatment is for the low thyroid levels it causes. Many people have found that 100% gluten-free diet is helpful in reducing Hashi flares, symptoms and eventually antibodies.




Thanks Clutter - pretty much as I thought. I’m slowly educating my GP so wanted to be sure I was right in my assumptions. I’ve shown him Dr Toft’s most recent article in the latest edition of the

Edinburgh RCP journal, Perspective, ‘A Counterblast to Guidelines’ which was the turning point.

Thanks for your help.


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