Thyroid UK
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Confused by T numbers!

Hi am bew here :)

Can anyone help at all with the Hypothyroidism T levels and what I need to know about my condition?

I have only just stumbled across this forum and feel now feel extremely naive about ny condition and whether I am getting the right treatment!

The pain I am getting in my shoulders and hips/legs is excruciating and my GP is telling me I need physio?

I can't help but feel like I am not being heard properly!

Can anyone offer any advice?  Even just a little hello and you've come to the right place is ok too ;) x

18 Replies

Hi welcome to the forum bird girl..... The more knowledgeable will be along soon 

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Hi! And thank you for the warm welcome Pixielula :)


Your welcome 


I am pretty new here as well. However I have learned more here than in many, many years of going to my PC and therapist.   

Still learning but I'm feeling better just having more info and being able to negotiate all of this on my terms.  

I know it will be a long battle but at least I've put one step forward.  

Good luck with your journey.  I'll follow along as we both travel to health.  

I'm not an expert on anything to comment but I'll be a sounding board and a smile when you need one.  All of that has helped me tremendously so it's nice to pay it forward.  



The T levels, in a very simplified format :

TSH = Thyroid Stimulating Hormone. This is a hormone produced by the pituitary, NOT the thyroid. Roughly speaking, when thyroid hormone levels fall, the pituitary releases TSH in response. The more the thyroid hormones fall, the more TSH is produced.

T4 and Free T4. T4 is the main hormone produced by the thyroid (in terms of quantity). It isn't a "real" hormone with biological effects, it is actually a pro-hormone. This means it is the raw material required to create the really important hormone called T3. Free T4 is the amount of T4 that is actually available to the body to convert into T3.

T3 and Free T3. T3 is the active hormone - the one that boosts the metabolism of the cells in the body. Every cell in the human body needs T3 to "make it work". People with an overactive thyroid (hyperthyroidism) have too much T3, people with an underactive thyroid (hypothyroidism) have too little T3. Free T3 is the amount of T3 actually available to the cells in the body.

Doctors will tell you that all they need to know is TSH. Many patients would beg to differ.


I should have mentioned...

The higher the TSH, the more T4 the thyroid produces. The thyroid also produces some T3 directly, but most of the T3 in the body is produced in tissues throughout the body e.g. brain and heart, by conversion from T4.


Think we've gone beyond begging to snarling, HB!


For a very good book on the thyroid, I would recommend this book :

I found it really helpful when I was trying to learn things from scratch.

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Hello Bird Girl

For web sites try the ThyroidUK site (even if you don't live in the UK)

and STTM which stands for Stop The Thyroid Madness

Learn plenty - argue with your doctor if you need to - don't be fobbed off.


Hello, and welcome, have you got a print out if your latest results, just that if you have it may be easier to explain the 'T's' by telling you what your T4 T3 etc is doing 😊 Jill X 

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Thank you ALL for such informative and warm welcomes! x

I am onto researching all about it today including ringing the docs to find out everything my last blood test contained to try and build a picture

I have a feeling I am only just starting out on a very long journey but am glad I have come to the right place!

Thanks again

Bird-Girl xx


Okay, apparently my last test results 4 weeks ago (before they upped the Levothyroxine to 175) were TSH 7.9 and FreeT4 17 but they didn't test for anything else

My journey begins....


Hi, you need to ask them the ranges, as each hospital have their own, but already can tell you your tsh is high, idealy better 1 or under, you are entitled to ask your surgery for a print out of your results, even if they have a moan you are entitled to them, 😊


That's great, thank you! :)

I am swatting up all of this info before I go to the doctors next Thursday for an appointment to discuss all of this - I will also be having a blood test to determine things afterwards so I may be able to get him to do bloods to test for other things as well like the FreeT3, Vit D and B12 as well as my T4 and TSH.

I am going in armed that's for sure! :D


It's very difficult to get FT3 tested on the NHS - they Don't think it's necessary!

It would be as well to also ask for antibodies : TPOab and TgAB. And for folate and ferritin as well as vit D and vit B12.

When you have a test, it needs to be early morning - no later than 9 o'clock. You should fast - just drink water - and leave 24 hours between your last dose of Levo and the test. That way, you will get the best results. :)


To make sure you get a good dose of Levothyroxine prescribed you need to have you blood test done first thing in the morning without having taken your Levothyroxine for 24 hours before, so if you take it at night, skip the previous night's dose until after your test. If you take it in the morning don't take it till after the test. It also helps if you don't have breakfast (you can drink water) till after the test. TSH varies throughout the day and is highest in the morning.

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Ah - I did wonder this and I was told that fasting wasn't needed for thyroid test?!

Also, it is a bit tricky as I suffer with diabetes...however my appointment is early morning so I will attempt that this time.

Thanks for your post!


The reason for the "rules" given by eeng is that doctors dose by the TSH. If the TSH of a hypothyroid person drops they will either deny treatment is required, or lower the dose of levothyroxine the patient receives, depending on which stage the patient is at.

So the "rules" are to give the highest possible TSH, and the lowest possible Free T4 (and Free T3 in the unlikely event it ever gets measured).

TSH - there is a circadian rhythm to the production of TSH (i.e. the amount produced varies over the 24 hours of the day), and the highest level is produced in the middle of the night. Since we can't get blood tested then we do the next best thing and get tested as early in the morning as possible - preferably before 9am.

TSH - there is some (weak) evidence that eating lowers TSH, so people fast before the test to avoid the TSH dropping. In the case of someone who is diabetic I would suggest eating as normal to avoid any problems, it isn't worth getting into difficulties over this one.

Free T4 and Free T3 - Taking Levothyroxine or any other thyroid medication will raise the levels of FT4 and FT3 very quickly, so we wait until after blood is taken to take meds.


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