Thyroid UK
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TSH reading off the scale for >12 years!

HI, I understand that the measurement range for TSH (thyroid stimulating hormone) is 0.4 to 4.0ml. I have had 22 readings over the last 12 years, and they have all been well below 0.4. In fact, they have been <0.05 and the medical printout says "outside reference range".

Within the same period my free T4 readings have always been within the acceptable range (9.0 to 25.0).

I suffer from a range of symptoms including fatigue, brain fog and lack of enthusiasm.

Could anyone provide any insight into these readings. My GP does not understand them.

7 Replies


TSH 0.05 with FT4 and FT3 within normal range indicates subclinical hyperthyroidism. What was your last FT4 result (please include the range)? If you've had ferritin, vitamin D, B12 and folate tested please also include the results and ranges.


The last reading a few weeks ago for T4 was 15.7. Over the years, it has ranged from 13.1 to 20.7, which I understand is well within the normal range.

Do not know measurements for vitamin D etc, so either they have not been done, or I do not remember (-:)



T4 15.7 is unequivocally euthyroid so although TSH is low I don't think your symptoms are likely to be thyroidal. Ask your GP to test ferritin, vitamin D, B12 and folate. Low/deficient levels can cause fatigue, brain fog and low mood.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


Do you have a free t3 result?


Thanks eljii


With under the range TSH and T4 (I'm assuming it is Free T4) in the lower half of the range you may have secondary or central hypothyroidism.

This is where your Free T3 level is vital for getting an accurate diagnosis.

If it is high then you might have subclinical hyperthyroidism as Clutter said.

If it is low then you may have secondary hypothyroidism as I suggested.

If it is reasonable then you are euthyroid (i.e. your thyroid is normal) and your symptoms may be caused by something else e.g. low minerals and vitamins.

Since your doctor is unlikely to help you (he hasn't done for 12 years so why would he change now?) you have a couple of options.

1) Change your GP - see a different GP in the same practice, or change practice altogether. Then see if one of them would agree to test your Free T3.

2) Stay put, pay for your own private testing and ask us for advice on the results. You can get the basics done - thyroid function testing, antibody testing, and the essential minerals and vitamins - for £99 from Blue Horizon.

The specific website you need is

Look for the "Thyroid Check Plus Eleven". The Collection method you need to order is "Microtainer (collect at home)".

What happens :

1) You make the order. A kit gets sent to you through the post. It contains full instructions, mini test tubes, lancets to prick your fingers for a blood sample.

2) On the day when you are ready to do the test, do the blood collection around 7am - 8am. (Thyroid testing should be done first thing in the morning.) Don't eat in the morning before the blood collection, and don't drink anything except water. Don't be dehydrated either.

3) Package up the bits you need to send back to BH and take it to the post office the same day you do the collection. Ask for "Special Delivery Guaranteed by 1pm".

4) Wait for results which are sent by email.


TSH is NOT a thyroid hormone so I ignore it. Do not get bound up in numbers its how you FEEL that counts not numbers.

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