What my GP said 🤔

[Autumn8]

Just got me thyroid test results.

TSH 0.01 ( 0.3-5.0)

T4 5.7 pmol (7.9-16.0l

T3 3.5 (3.8-6.0)

These are all below reference range so abnormal. GP will retest in 6 weeks and may consider prescribing Thyroxine if needed. Told me my thyroid is suppressed. How can it be suppressed if the levels are all below reference range? 🤔

Anyone offer any insight pls? T.I.A.

Didn't find GP at all helpful.

[Judithdalston]

can you add the references so we can see where they are in / below range?

[Autumn8 in reply to Judithdalston]

Just added levels. Thank you

[SlowDragon Administrator]

looking at your previous post

You currently take NDT - this will almost always significantly lower or suppress TSH

[humanbean]

Told me my thyroid is suppressed. How can it be suppressed if the levels are all below reference range?

I'm assuming that you are currently untreated for any form of thyroid disease.

90% of patients with hypothyroidism have Primary Hypothyroidism. In that situation the problem originates from a thyroid that doesn't work well.

But judging by your results you probably have Secondary or Tertiary Hypothyroidism, otherwise collectively known as Central Hypothyroidism (CH). In that situation the problem originates with a pituitary that doesn't work very well (secondary), or a hypothalamus that doesn't work very well (tertiary).

In healthy people the thyroid, when stimulated by TSH, makes thyroxine (aka T4) and about 20% of the body's supply of T3 which is the active thyroid hormone needed by every cell in the human body. The pituitary makes TSH (Thyroid Stimulating Hormone) having been stimulated by TRH (Thyrotropin Releasing Hormone) which is produced by the hypothalamus. Note that Thyrotropin is just another name for TSH.

In CH it is perfectly possible for the thyroid to be completely healthy, and it is the fact that the thyroid isn't being stimulated by enough TSH that is causing your problems.

Unfortunately, doctors have been taught that CH is very rare, and as a result if they suspect a thyroid problem they assume it must be caused by a dodgy thyroid. And that is true with both hypothyroidism and hyperthyroidism.

There is a chance that your doctor might assume you have hyperthyroidism (overactive thyroid because your TSH is very low), and will ignore the fact that your thyroid hormones are also very low. Very low Free T4 and Free T3 should prompt a diagnosis of hypothyroidism (underactive thyroid because your thyroid hormone levels are low).

Since doctors are so convinced that CH is rare I'm not sure what your doctor will do when faced with evidence that you have it. He ought to prescribe Levothyroxine, but he might abdicate responsibility and refer you to an endocrinologist. (And sadly, Endos think CH is very rare too, and are reluctant to diagnose it.)

The pituitary makes eight hormones. If your pituitary is not making any (or enough) TSH then it is also possible that other hormones are not being made in sufficient quantities either, so an Endo should test all of them in your situation. But how often that happens, I really don't know.

In cases of CH I always have this mental image of a doctor's head exploding because they think CH is so rare.

[Jazzw in reply to humanbean]

Autumn8 was taking Thyroid-S but stopped a few weeks ago. I think it may have meddled with the pituitary-thyroid axis?

Not saying it couldn’t still be CH—it might always have been—but it could just be a question of needing to wait longer for TSH to rise again.

[Jazzw]

Your GP used odd terminology. Your thyroid isn’t suppressed—but your TSH is.

Which is to be expected on NDT. Did she know you’re on NDT?

[greygoose in reply to Jazzw]

I was going to say the same thing. But many doctors use the terms 'TSH' and 'your thyroid' as inter-changeable. Probably because they don't understand how any of it works!

TSH is not 'your thyroid'.

[tattybogle]

your TSH( Thyroid Stimulating Hormone) is what is 'supressed', not your thyroid.

TSH is a signal from the pituitary( brain) to the thyroid , asking it to try and make more T4/T3

T4 and T3 are the thyroid hormones that make the body work.

if all is working as it should , when the pituitary senses levels of T4/T3 are too low the TSH level will rise , to stimulate the thyroid to make more T4/T3

if the TSH is so low it's not measurable it's called 'supressed' .

your TSH should have risen quite high in response to the very low levels of T4/T3, but for some reason it hasn't .

If repeat test confirms these results ~ then this can indicate a pituitary problem , GP would probably need to arrange further testing with endocrinologist as if there is a problem with the pituitary it can also involve the other hormones the pituitary produces)

When there is a problem with the pituitary not making enough TSH , it leads to hypothyroidism because there is not enough TSH to ask the thyroid to make more hormone ... so you end up with low T4/T3.

This is called Secondary/ Central hypothyroidism .... because the problem is not with the thyroid itself, thyroid itself is fine , its just not being 'asked' to make any more T4/T3 , so it isn't,, the thyroid issue is secondary to a pituitary problem .

does that make more sense now ?

so in a way , yes ,your thyroid is also supressed .... ie. it's not being asked to make as much T4/T3 as it should.

[tattybogle in reply to tattybogle]

edit .. oh i didn't realise you were already taking NDT ?... if taking thyroid hormone already my reply might not be relevant .

[Autumn8 in reply to tattybogle]

No, not taking NDT anymore. Stopped this weeks back, did not agree with me. Thank you for your reply.

[Jazzw in reply to Autumn8]

Ah. But… it can take quite a while for a TSH that’s been suppressed by NDT several weeks and sometimes months to start climbing back up again.

Which is probably why your FT4 and FT3 are so low.

I bet your doctor is a bit puzzled. It often doesn’t take much. But in this instance, your suppressed TSH isn’t telling the story they think it’s telling.

[Autumn8 in reply to tattybogle]

Thank you. Very infornative