T4 in range but non existent TSH

[OrangePippin]

Hi everyone, I’m new here and would be very grateful for any advice. I’ve had an overactive thyroid for about eighteen months now but have resisted surgery and RAI. My T4 has come down steadily from 53 to 12.6 (top of my lab range is 15.1). But my Endo clinic is wanting to increase my carbimazole (at a point when I was starting to want to halve it from 10 mg to 5 mg) because my TSH is still not registering. Is this reasonable? The thing is I am starting to feel terrible (no energy, depressed and headaches). I basically only feel well when my T4 is up around the top of the normal range, so if they increase the Carbimazole surely I’ll start to go hypo? I already feel hypo! I’ve also put on a stone in weight in the last six weeks. I can’t give any T3 numbers because the lab doesn’t do T3 even when it’s requested.

Why is it so important to get my TSH to register? Won’t it catch up on its own eventually?

Thank you so much to everyone on this forum, you are all very helpful.

[Coconutty]

Don’t let them dose you by TSH. That will recover eventually, but there’s a big lag. I would agree with you that a reduction to 5mg is the more sensible option. Do you know what your FT3 is doing?

[Coconutty in reply to Coconutty]

Sorry just noticed you said they won’t test it.

[Coconutty in reply to Coconutty]

By the way, the NICE CKS guidelines say to dose by FT4 so you can use that as ammo:

cks.nice.org.uk/hyperthyroi...

“Titration-block regime — a thionamide is used and the dose adjusted every 4–6 weeks depending on free thyroxine (FT4) measurements. A dose reduction may be needed if the FT4 level falls to low-normal or below the reference range, or the TSH level increases, indicating the development of hypothyroidism. The aim is to allow endogenous synthesis of thyroid hormone to continue.”

So, very important, the aim is to keep producing thyroid hormone, not grind you into the ground until TSH increases.

[OrangePippin in reply to Coconutty]

Thank you so much Coconutty this is just what I needed x.

[OrangePippin]

Hello and thank you for your thoughts. I have been told I don’t have Graves, just thyrotoxicosis. But I do wonder if the same thing might be happening with the pituitary thyroid feedback loop as I feel well only at the top of the range. A goitre developed after the birth of my third baby but I felt fine for over 30 years, blood tests all the same: ‘hyperactive end of normal’. Things only started to change about four years ago when we moved house (at the same time as a difficult tooth abscess). Could have been coincidence but it does seem as if one or other might have put me on overload and kicked my thyroid problems off. It’s academic now anyway.

Yes I agree re the RAI, they tried so hard to push it every single time I saw anyone, plus at least two letters from the consultant. They make it sound like nothing, like having your tonsils out!

Ps It just occurs to me that I could try and find out what my TSH used to be when I was at the overactive end of normal all those years. Might be helpful.