# How to calculate rt3?: Hello In my country we... - Thyroid UK

## Thyroid UK

131,718 members154,140 posts

Hello

In my country we use:

0.22-0.54. Nmol/l. My was 0.33 rt3

So that is: 14.33- 35.16 ng/dl. 21.48 rt3

I am not sure if I just can convert all number to ng/dl

So I have to be 2 point above but its a different range then 10_24 ng/dl. That would mean if I calculate that 12 is a good level, 2 points above it's 14%.

14% of my range is 0.26 nmol/l

14% of the other ng/dl is like 17.23 ng/dl

That would mean I am just a little high. Because it looks high 21 but you use other ranges and I am 14 in yours? I hope compared it good? I use the endo rt3 conversion model but I have difficulty with the 2 point above bottom comparing??

I am doubting because some told me that 21 ng/dl is to high that it does not matter wich range you use? That in my lab starting at 14.33 is just because more people did have rt3 high and that is why they start so high. Is this true? Can somebody help. How would no know if rt3 is low if the bottom level starts at 14.33 ??

5 Replies
greygoose

It does matter what range you use. You should always use the range used by the lab that did the blood analysis. But, you don't need to convert or calculate. A range is a range, and if you are inside it, it's OK. In your original test - 0.22-0.54. Nmol/l. My was 0.33 rt3 - you are within range. It doesn't need to be translated for us to understand that. You do not have high rT3.

Besides, rT3 is a red herring. It doesn't mean much even if it's high. It means you have a problem somewhere, but the test does not tell you where. So, it's other tests that are more important. Like your FT4. If your FT4 is very high in-range, or over, then you will have high rT3, that is a given. But, it's ok.

Or, you could have high cortisol or low ferritin or low-calorie intake, or an infection causing high rT3. In which case, it is those things that you should address, and not be worrying about rT3.

But, you don't even have high rT3, so there's no problem.

Hi greygoose

Thank you for your answer. But I am correct that if i do the conversion I am at 14 on a range from 10-24? It is just confusion as some say I do have very high rt3. I just want to know how to compare.

I couldn't tell you. I'm terrible at maths!

Some people talk a lot of rot about rT3! Forget them. And forget it. Knowing your level of rT3 just won't get you anywhere. It is not the missing link that some people believe.