Thyroid UK

Are the TSH tests in the U.K. Different to those in the USA??


I'm having trouble getting my gp to up my Levothyroxine and need some help.

My latest TSH was 4.7 (0.4-5.5 range) and T4 was 14 (12-18 range). She seems to think that now I'm in range I shouldn't up my dose as otherwise I risk osteoporosis from being over medicated.

I told her that I feel my TSH is still way too high and that it needs to be in the bottom 1/3 of range to be optimal. I mentioned about the range in the UK being way too high and her reply was that they used "different assays in other countries" and therefore it wasn't that the UK range was too high it was just that the tests were different.

Does anyone know if that's true? I would like to go with some decent evidence so she can up my dose without just brushing me off?

I was only on 25mcg at the time. She agreed to raise it to 50 but that has only lowered my tsh 4.2 so hardly any difference even though it's doubled my dose. She made me get a calcium and vitamin d check last test but they were both in range all be it the lower ends.

I do feel better than I did up at 6.7 but I still feel it's not right and I really want to feel better.

Any advice on whether what she says about other countries considering a much lower level of tsh as being hypothyroid? And any other ways I can get her to up my meds?

12 Replies


Other countries have set a lower level of TSH to determine hypothyroidism than UK. You are under medicated to have TSH so high when you are taking Levothyroxine. The goal of Levothyroxine is to restore the patient to euthyroid status. For most patients that will be when TSH is 1.0 or lower with FT4 in the upper range. FT4 needs to be in the upper range in order that sufficient T3 is converted. Read Treatment Options in Email if you would like a copy of the Pulse article to show your GP.


I think osteoporosis is more linked to being under medicated. I know of 2 people with it who are undermedicated, possible 3rd but she isn't diagnosed as having osteoporosis yet. I am not totally sure about the tests being different. I know that in many other countries they class it as raised at a lower amount. Yours still is raised. It really needs to be below 2 for you to feel fully better. May be worth trying to research this though. Sounds as if she is just making it up to get out of upping your dose more.


you need a different GP and a copy of the Pulse article for one

healthy people have a TSH of 1.0 or below

free t4 and free t3 both well into upper level of their ranges

your gp has failed to understand the basics of treating hypothyroid and is keeping you ill


Sorry it's below 1 yes not 2 my mistake. Mine is below 1 at the mo and feel better. x


Our resident test expert is diogenes - who may be able to provide definitive clarification.

Tests like the TSH test are manufactured by a number of companies. These companies, like most commercial organisations, sell their products when and where they can. There is no geographic border where Company A sells in the UK, Company B sells in the USA, and there is cross-over.

I suggest you read this thread:

The choice of reference ranges, especially the top of the TSH range, is a disputed topic.

On a similar range to your test, my first TSH test result was about 2, and I was diagnosed when I was just over top of range. I asked for that first test because I thought something might be wrong. By the time it hit top of range, I was certain something was wrong - and pretty sure what it was.

There is much argument about the issue of osteoporosis. There is, though, zero evidence of osteoporosis caused by thyroid hormones when TSH is within range - even at the very bottom. And there is evidence that inadequate thyroid hormone negatively affects the bones (and much else).

Medics see osteoporosis in, for example, Graves disease, when patients have thyroid hormone levels two, three or more times what they should be, and often unmeasurably low TSH. They then somehow assume this will be the case when TSH is still within range! On no basis whatsoever except some hunch or misremembered comment.

Your GP is out of date, out of her depth, and would do everyone a favour if she were out of office next time you visit. You need a GP who has some understanding.

My last TSH was something like 0.5. My GP was perfectly happy.


A link that may help you :

it shows a graph of TSH in a healthy population. As you can see the distribution is highly skewed towards the lower end of the reference range and the majority of the population have a TSH well below 2.

Read all the blurb on the page - it is worth the effort.

The data for the graph came from this paper :

The best part of that paper in my opinion is the right hand half of table 3 showing the mean TSH for groups of healthy people in different age groups and for each sex.


Very impressed by the thoughtful, evidence based responses here. Not my post of course but if it were I'd be very satisfied.


Would you be able to change your doctor? I'm in the states and actually went to three before I chose the one I have had now since pre-hypothyroid. At the time I had insomnia, and since I am also aspergers...anxiety that comes along with it. Since you already have diagnosis maybe you could shop around? You deserve a physician who will listen to you! Do you have a primary care physician? or is that the one you are talking about in your post. Most insurances allow you to get second opinion.


TSH ranges in various test sources differ by not more than 10%. This test happens to be the most consistent unlike the FT4 and FT3 tests. Recent papers demonstrate that adequate FT3, the hormone active in maintaining health, does not occur under T4 only therapy until TSH is less than 1, and less than this by quite a margin. The thyroid profession hasn't realized the healthy range for TSH isn't appropriate for treatment.

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The recent Rotterdam study showed no correlation between osteoporosis, heart disease and low TSH. Low TSH is only associated with those diseases when coupled with very high FT4 and FT3 as in Graves. GP not knowledgable.


Thank you all so so so much. I truly appreciate your considered and helpful responses. I will read all the links and posts carefully and go armed to my next appointment. I'm so glad to have this site as I was feeling so lost and disheartened. You've given me hope that I can persuade and I will certainly ask to see a different GP going forwards if they will let me.


in the santa clara county ,calif usa there are different tsh number just depends what clinic you go for i would have to look up whats the difference between 25mcg and just 25 mg just in santa clara county at good samarition hospital has the tsh at 1.0-0.1 if mine was at that i would be laying on the floor not be able to move very far now stanfords is 0.40-4.0 mlu/l mine is 6.4 right now and i feel better than when it went up my only problem now is my mild asthma going to have act scan and then see my pulmonary doc

i`am just going to make a wild guess it all depends on every person system and i know you don`t have a lot of choice in the UK maybe the people should ask for a better health care system we have a some what good health care system which trump want to get rid of he will make a big mistake and get impeached and kicked out


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