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My 21 year old son had just had his bloods checked and the results are as follows

Serum TSH . 3.69. (0.35 - 5.00)

Free T4 . 15 (9.00 - 22.00)

Recommendation by lab is to take on current dose of thyroxine 100mg

I'm still struggling to interprete results but am I correct in thinking his TSH should be lower and his FT4 should be higher if so should the dose not be changed ?

6 Replies

Lanvere Yes and yes. As he is diagnosed and treated with levo, his TSH should be around 1 and his FT4 (and FT3) in the upper part of their ranges.

Was this an NHS test? What has the doctor said? How does your son feel?

Dr Toft, past president of the British Thyroid Association and leading endocrinologist, wrote this in a Pulse Online magazine article:

"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance.

But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."

If you email she will let you have a copy of the article which you can print out and your son can show his GP and discuss an increase in his Levo.


Thank for info ... In his words he feels really ill and dying .... He was diagnosed wuth Hashimotos and because of his mental instability the Endo put him on thyroxine as a trial ... He sufferers terrible from anxiety and panic attacks... His cortisol was low and and ACTH test was done but the Endo thinks his result is "probably " normal which is my view is not a acceptable either they are normal or they are not ... Done some research on adrenal fatigue and started him on magnesium which Seems to have stabilised him at the moment mentally ... What I don't understand is his previous TSH result in March from BH was 0.82 and the same month from GP 1.5 with no thyroxine treatment ... Why with thyroxine is it going up x


Did he have an overnight dexamethasone suppression test a few months ago, and wasn't his cortisol high, at 65 nmol/L (below 50 being normal)?


Lanvere I imagine the reference ranges for BH doctor are different hence the difference in the TSH??? It doesn't matter what the ranges are though, it's where in the range that matters.

I'm confused :

"What I don't understand is his previous TSH result in March from BH was 0.82 and the same month from GP 1.5 with no thyroxine treatment ... Why with thyroxine is it going up x"

Was he on Levo in March when the BH test was done? (I'm reading that he wasn't)

Was he on Levo when the GP test was done later that month?

How long has he been on Levo? What was the starting dose? What is his dose now?

As he has Hashi's is he 100% gluten free and supplementing with selenium, both of which help reduce antibody attacks?

I can't help with the cortisol/ACTH, I only can understand the Genova adrenal test, sorry .


How long has he been on 100 mcg?


Wow how interesting will research thanks x


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