Is suppressed TSH more likely with secondary hy... - Thyroid UK

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Is suppressed TSH more likely with secondary hypothyroidism?

Bearo profile image
14 Replies

Calling all the members who have Central hypothyroidism - is your TSH suppressed?

I may have Central hypothyroidism but it’s not diagnosed. An appointment has been made for me to see a GP on Thursday after I wrote a letter complaining that my dose of Levo has been reduced (by text - no consultation). No reason was given for the dose reduction but as my TSH was it’s usual 0.03 at my recent blood test I can safely assume that is the reason.

As part of my argument for keeping my dose as it was I’m going to say that I may have Central hypothyroidism and so TSH should be ignored and FT4 considered instead. My FT4 is about 60% through range, so not over medicated. Of course FT4 should be considered anyway, but just adding arrows to my bow.

If suppressed TSH is more likely with Central hypothyroidism I can say that, too. But is it? I think the only explanations I’ve read here for suppressed TSH is longish periods of over or under medication.

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Bearo
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greygoose profile image
greygoose

If you have Central Hypo, the TSH is totally useless as a guide to dosing. But, very few doctors have even ever heard of Central Hypo! So, not sure that that's a good argument.

But, question is: if you have CH, how did you manage to get diagnosed in the first place? Do you have your blood test results from when you were diagnosed? Because you cannot tell once you get onto thyroid hormone replacement.

I think the only explanations I’ve read here for suppressed TSH is longish periods of over or under medication.

You wouldn't get suppressed TSH with under-medication. And, it doesn't even have to be over-medication for your TSH to become suppressed. Due to the way the pituitary functions, it can be satisfied with thyroid hormone levels in the blood even though other tissues are starved of hormone, and you're still hypo. That's just one of the reasons why dosing should never be done by TSH only. If only doctors had half a clue!

Bearo profile image
Bearo in reply to greygoose

At diagnosis TSH was 4.9, and FT4 was 10 (12-22). anti body test was negative.

So TSH was raised, but not very high considering low FT4. No GP has ever suggested Central hypothyroidism but I’ve always thought it was a possibility.

greygoose profile image
greygoose in reply to Bearo

Well, you're right, that does look like Central Hypo. But the reason no GP has ever mentioned it is that they probably have never heard of it. Most doctors seem to assume that everyone is blessed with a perfect pituitary that never goes wrong!

Have you had any other pituitary hormones tested, like HGH or ATCH? How's your cortisol?

Bearo profile image
Bearo in reply to greygoose

Thanks for your reply, greygoose, I’ve never had any cortisol testing. I could ask for the serum cortisol test.

greygoose profile image
greygoose in reply to Bearo

Yes, you could do that. :)

Nomad12 profile image
Nomad12 in reply to greygoose

I am trying to find out the cause of my Hypothyroidism and if I have central Hypo (my doctor is no help in finding the cause, just said hypo is so common now and prescribed levo). I privately do my tests now and my TPOAb is 19.4 (range >34) and TgAb is 95.9 (range >115). So based on that am thinking I have central, though slightly concerned the TgAb is quite high in the range but maybe as long as it is under that is ok... Really wanted to rule out Hashimotos, so I could look at other aspects. Thank you for any advice you can give. These are my blood tests from when I was diagnosed - TSH 11 (lab 0.3 - 5), FT4 12.7 (lab 9 - 25).

greygoose profile image
greygoose in reply to Nomad12

With a TSH of 11 it's very unlikely to be Central Hypo. TSH doesn't get that high with CH. But with a TgAB that high there is always the possibility of Hashi's/Ord's.

You cannot rule out autoimmune thyroiditis on the basis of one negative blood test because antibodies fluctuate all the time. With TgAB, high levels could be due to a number of things, but with such a low FT4 it's more likely to be thyroid than anything else. You have to look at all the numbers in conjunction with each other. Besides, some Hashi's people never have over-range antibodies, so I'd go for Hashi's, myself.

Your doctor isn't interested because he knows that whatever the cause, it's irreversible and the treatmentis exactly the same. You cannot treat the autoimmune side of Hashi's, and you cannot 'cure' a damaged pituitary - although CH may have implications for other hormones, so that's necessary to know. But, all you can ever do for the thyroid is take thyroid hormone replacement to replace the hormones it can no-longer make.

Nomad12 profile image
Nomad12 in reply to greygoose

Thank you so much for your reply, that has really helped, have been going round in circles up to now. Just bought the book no grain no pain, so think I will try diet now to see if I can help the joint issues.

greygoose profile image
greygoose in reply to Nomad12

Yes, Hashi's people are often gluten-sensitive so that might help. Have you been tested for Coeliac Disease? If not, it might be a good idea to ask your doctor for that before embarking on a gluten-free diet.

radd profile image
radd

Bearo,

You can say the inverse correlations between TSH and thyroid hormones seen in healthy people often become skewed in people who medicate.

The very fact we have to medicate means there has been alterations within the HPT axis, and for some a down-regulation in base-set possibly caused by years of being left undiagnosed.

Apart from central hypothyroidism there are other reasons why TSH may remain low when we are medicating such as medicating T3, recent/long term non-thyroidal illness, TRAb's even in the presence of Hashi, resistance to thyroid hormone, and other but I think it better to keep your discussion simple and just emphasise the disconnect between your TSH and your thyroid hormone levels and hopefully by seeing the actual results in front of him, your GP will understand.

helvella profile image
helvellaAdministratorThyroid UK

In my view, "suppressed" is entirely the wrong term, the wrong concept.

If you turn a tap off, the water flow reduces. It is, we could say, suppressed. Could be anywhere from unsuppressed (full flow), through, partially suppressed (a gentle flow), to fully suppressed (none at all).

But if the pipe has no water supply, it would be a ridiculous concept.

There just isn't any water. It matters not what the suppression mechanism is (a tap!). Nor where it is set (open or closed, on or off).

In TSH terms, I consider suppression to be the effects of insufficient TRH and too much thyroid hormone (T4 and T3 or a combination) which turns the pituitary down.

Whereas central hypothyroidism is saying the pituitary isn't working to specification!

I understand this is not-picking and pedantic. But it isn't you, Bearo, I am pointing at. It is the medical system that is indeed likely to point at low TSH and speak the word "suppressed".

Suppression is a process.

Not working /non-functional is a state.

Bearo profile image
Bearo in reply to helvella

So you’re saying suppression should be a deeper understanding of what’s going on rather than some random number without looking at causes and mechanisms? Apologies if I misunderstood even your basic analogy - brain not in gear at all!

It’s pretty annoying that there isn’t agreement on measurements that constitute suppressed let alone understanding of suppressing mechanisms beyond overmedication .

0.002-3 (my measurement) falls between immeasurable and 0.I /0.04 /0.27 or whatever lower measurement is deemed acceptable.

I think mine is just not working very well. There’s not too much going on to suppress it, that I can undo so it suddenly responds. I’ve done the trial on a lower dose and my TSH hasn’t moved - well, it decreased by .01, but that was probably blood test timing.

I think I was hoping to blind the GP with science, by using Central hypothyroidism rather than having to argue that my mid range frees don’t deserve to be decreased.

Nanny23 profile image
Nanny23

Hello. My TSH is always suppressed since adding T3 to my T4. I feel much much better. My dr. Did mention central hypothyroidism. I asked and she said it’s treated to same with thyroid hormones.

Bearo profile image
Bearo in reply to Nanny23

Thanks. Adding T3 does tend to suppress TSH, central hypothyroidism or not. Yes, my GP said it’s treated the same so no need to get extra tests!

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