What is the tsh reference range for combined t3... - Thyroid UK

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What is the tsh reference range for combined t3 and t4 therapy?

agggieswell profile image

Can someone advise what the correct tsh reference range is on combined T3+T4 therapy. I am taking 75mcg of levothyroxine and 40mcg of liothyronine. I have been hypothyroid for 10 years and have never felt this awful. My tsh is 2.72 and my doctor gives me a reference range of between 0.27 and 4.2. Is this correct for someone who is taking combined t3 and t4 therapy? I have requested that my t3 is tested on 2 occasions now and it has been declined by the hospital because my tsh is "normal". I am sure i have read somewhere that on t3 therapy the tsh can be supressed to below 1. Is this correct?

8 Replies

There are no fixed ranges. They vary from lab to lab. But, with the TSH you don't need a reference range to know that your TSH is too high. With a dose like yours, one would expect it to be suppressed - suppressed is below 0.1.

So, that raises question about your absorption. Do you always take your levo and your T3 on an empty stomach, at least one hour before eating or drinking anything other than water? Do you take any other medication or supplements at the same time as your hormone?

Your doctor should know better than to try dosing T3 with just the TSH. Your FT3 does need testing, you're right. But, obviously your doctor knows nothing about thyroid.

Thank you greygoose. Yes I always take my medication on a completely empty stomach with not even a sip of water! I was advised by the hospital to only wait half an hour before eating or drinking but I have noticed that on here people are advised to wait an hour. I do have IBS too and have followed all the recommended time intervals for vitamin supplementation. I'm seeing a private practitioner next week I just can not stand this anymore.

Actually, you should take your hormone with a large glass of water to make sure it gets down into the stomach. If it gets stuck half-way down, you won't absorb it. Try taking it with water, and waiting an hour be fore eating or drinking anything other than water. :)

SlowDragon profile image

How do take your Levo and T3 ? Do you split the T3 into 2 or 3 doses or single dose

For full Thyroid evaluation you need TSH, FT4, FT3 plus TPO and TG thyroid antibodies and also very important to test vitamin D, folate, ferritin and B12

All thyroid tests should ideally be done as early as possible in morning and fasting. When on Levothyroxine, take last dose 24 hours prior to test, and take next dose straight after test. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, GP will be unaware)

If also on T3, make sure to take last dose 12 hours prior to test

Is this how you do your tests

Private tests are available. Thousands on here forced to do this as NHS often refuses to test FT3 or antibodies or vitamins


Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

If antibodies are high this is Hashimoto's, (also known by medics here in UK more commonly as autoimmune thyroid disease).

About 90% of all hypothyroidism in Uk is due to Hashimoto's. Low vitamins are especially common with Hashimoto's. Food intolerances are very common too, especially gluten. So it's important to get TPO and TG thyroid antibodies tested at least once .

Link about thyroid blood tests


Link about antibodies and Hashimoto's



List of hypothyroid symptoms


Thank you for the information. I have just ordered a Medichecks Thyroid Plus and it came this morning. I'm sure I'll be back to you again once those results are threw. Thank you again. This site is a much valued lifeline.

Is there a way I can save your replies?

Treepie profile image
Treepie in reply to agggieswell

You could print them .

First, a lot depends on whether you have any working thyroid remnant left or not. If you have some, then a TSH around 1-1.5 might be OK, but if you have none at all, it should be below 0.5 (undetectable-0.5). Therefore since I don't think you or the doctor will know what thyroid activity you have if any, the best way is to go on your response to therapy rather than fixed numbers.

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