Thyroid UK
90,738 members105,091 posts

Interpreting Thyroid Test Results

Hi all. This is my first time on a forum, ever, but am seeking some advice.

I was diagnosed with an underactive thyroid at the age of 15 (21 years ago now!!) and have been on c.200/175mg of thyroxine for most of that time.

Last summer I had a blood test and my GP decided my TSH was too low (0.01 I recall) and started to reduce my dose which they continued to do and I am now on 125mg.

As a result of this, over the last 8/9 months I have again started to suffer the symptoms of hypothyroidism (I won’t bore you with them - you know what they are!!). Now my GP does routinely check FT4 and FT3 but my research tells me they should and thus I have asked for that at my recent visit as I am in complete dispair. The results came back as follows:

TSH: 0.99

FT4: 12.9

FT3: 3.0

They confirmed this was normal. From my symptoms and from what I have read, I disagree as the FT4 is at the lower end of the range and the FT3 I think is below? Which makes me think they are disregarding this result completely.

Now I am not 100% sure what the ranges are that the NHS use, so any advice on that would be welcomed, but also any thoughts on these results? I am due to see the doc later this week and want to go armed with reasons why these are not ‘normal’ and that I need my medication increased.

I’ve waffled, sorry, but any thoughts/advice would be appreciated!


6 Replies

What ranges did they give with these results? They are the numbers in the brackets given usually after the result.

It's hard to say without those ranges, but maybe they think they're normal because the TSH is in range, but it looks as if your FT4 and FT3 are low and you're symptomatic as a result. So in short, I think you're probably right.

What to do about it? Well your TSH is far from suppressed, so maybe your GP would be open to raising your dose "on a trial basis" to see if you feel better? You could list your symptoms and ask if you could try this? If they're unwilling, maybe you'll need to think about changing doctors. If you really can't get anywhere, you can buy medication overseas and increase your dose yourself, but it's much better if you can make some headway with your GP.

All this provisional because you haven't posted the ranges.


Thanks Blogsy2, I appreciate you’re response.

Annoyingly the didn’t share with me the ranges (got the results over the phone) but will follow up and ask the question as at the moment I am basing my interpretation on what I can find online and believe to be he NHS ranges, however this may not be the case!

I am hopeful that the GP will be supportive in upping the dose, just fee so rubbish at the mo! Am also curious about T3 supplementation with the GP’s monitoring (I don’t think they would prescribe it so would have to source it privately).

Anyway - will see what else I can find out and otherwise will see how I get on when I see her later in the week. Just find it all so exasperating, especially the wait between blood tests, appointments etc. All the whole you continue to feel awful, put on more weight etc. Etc.

Thanks again!x



You need the reference ranges from the lab that did your tests as they vary from lab to lab.

Ask at your surgery's reception for a print out of your results. Don't accept hand written or verbal results, mistakes can happen, so get a print out then put the results with ranges on the forum for further comment.

Have you had the following tested, if not then it would be helpful to get a complete picture as there may be some clues

Thyroid antibodies (TPO and TG)

Vit D





I have a friend and the ranges have not been on the report the doc issues the patient , is this a new way to control us 🤔

1 like

I have responded before with my opinion:

I believe that reference ranges should be covered by the second bullet point below. A bare number means nothing. It needs explanation.

What should an organisation send me?

You are entitled to be told if any personal information is held about you and if it is, to be given:

• a copy of the information in permanent form;

• an explanation of any technical or complicated terms;

• any information the organisation has about where they got your information from;

• a description of the information, the purposes for processing the information and who the organisation is sharing the information with; and

• the logic involved in any automated decisions (if you have specifically asked for this).

Some tests seem to be very much more standardised than others. However we know from experience that thyroid tests, especially FT4, can and do vary significantly.


Thanks all...

I’ll get a print out when I go into the surgery later this week, fingers crossed it will show me the ranges!!

SeasideSusie - not sure if I’ve had all of the tests that you list done, will check and if not will request. I’ve only through recent research become aware of the Thyroid antibodies test, so think this is definitely worth requesting too. Will see what I can do!

Thanks so much.x


You may also like...