Is it worth getting a private test for T3?

[FriedStuffWithCheese]

I was recently diagnosed with underactive thyroid and got a copy of my blood test today. I noticed there's no T3 result, but apparently this is not tested anymore and a quick search here seems inline with other NHS labs.

I'm seeing the nurse practitioner for my treatment and I am happy with her approach - she said to have another blood test after 3 weeks on medication and see her after to adjust again. And I'll probably need increases and tweaking to find my level.

So I'm wondering if testing T3 would make much of a difference at this point.

For info my results were

TSH 44.20 mu/L [0.3-5.6]

FT4 3.8pmol/L [6.3-14.0]

Many thanks

[SeasideSusie Remembering]

FriedStuffWithCheese

I'd say not to bother with FT3 at this point. It is very early in your thyroid journey, you need to get your TSH down and your FT4 up. We test FT3 to see if we are converting T4 to T3 well enough, and we can't see how well we convert until TSH is down to about 1 or below. So for now just go with your NHS tests.

The aim of a treated hypo patient generally is for TSH to be 1 or below or wherever it needs to be for FT4 and FT3 to be in the upper part of their reference ranges, if that is where you feel well. When you get to a dose of Levo that brings your TSH down to this level it might be worth testing FT3 then. But never test FT3 on it's own, it needs to be done with TSH and FT4, all from the same blood draw.

[FriedStuffWithCheese in reply to SeasideSusie]

That all makes perfect sense, thank you.

[NWA6 in reply to SeasideSusie]

Yep! Perfect answer from SeasideSusie 🤗

[shaws Administrator]

I really do not know why they test FT4 but don't do FT3.

With such a high TSH i.e. 44.20 you are definitely hypo. Increases every six weeks of 25mcg levo should reduce your TSH - the aim being 1 or lower. You will probably find that FT4 and FT3 will also increase (hopefully).