Thyroid UK
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6 week trial of T3 blood test results - doctor wants to see me!

I have just got my test results back from being on T3 for 6 weeks having been put on it on NHS prescription, by a private constultant via my doctor. The results are as follows:,

TSH 0.01 mU/L (0.35 - 5.50 mU/L)

T4 13.2 pmol/L (10.50 - 20.00)

T3 4.8 pmol/L (3.50-6.50 pmol/L)

This is on 20 mcg T3 a day and 100mcg T4

Before T3 the results were:

TSH 0.13

T4 20.10

T3 4.6

ranges as before.

The doctor has asked to see me but I cannot see her until next Wednesday. Can anyone shed light on how she might be interpreting these results? I am concerned that she is going to say my TSH is too low and take me off the T3 (probably because of the cost). However, I feel so much better on the T3 than I did on T4 alone.

Can anyone help please? Has anyone had a similar experience?

9 Replies

I should think she wants to see you re your TSH. They get very worried when your TSH goes below the reference range. She most probably wont have the experience of patients on T3 alone so will be unaware of the difference in the blood test results.

Your TSH is the same as mine. I am now on NDT. These are a couple of excerpt re being on T3 alone:-


For someone taking 100 mcg of T3, we expect your pattern of lab results—a low TSH and high T3. However, your TSH and T3 levels are irrelevant to whether you're overstimulated or not. Two studies we just completed confirm other researchers findings: these tests are not reliable gauges of a patient's metabolic status. Many patients taking T3 have TSH and T3 levels like yours but still have severely low metabolic rates. Their metabolic rates become normal only when they increase their dosages further. Their metabolic rates become normal and they have no detectable overstimulation.

In some cases such as yours, the patient's Cytomel dose may need to be reduced. But symptoms such as occasional heart pounding and anxiety are usually not due to a patient's Cytomel dose. I say this because when Cytomel is solely responsible, symptoms of overstimulation are consistent, not occasional.


Most endocrinologists subscribe to the practice guidelines of the American Association of Clinical Endocrinologists. When a patient such as you sees one of these endocrinologists, he’s likely to take her off T3 and switch her to T4-replacement. As many patients have told us, when an endocrinologist switched them to T4-replacement, they became ill and dysfunctional again. These reports are consistent with studies that show the ineffectiveness and potential harm of T4-replacement. The studies show that T4-replacement leaves many patients suffering chronically from hypothyroid symptoms[1][2][3][4][5][6][7] and gaining weight they can't lose through dieting and exercise.[8]


Thanks shaws. I do take thyroxine as well - 100mcg thyroxine and 20mcg T3. I was really hoping I could actually increase the T3 so that I could feel even better than I do now, but I would settle for feeling as I do now!

How do I get my doctor to understand that the test results are not reliable? I feel so much better now I am on T3. Having read the link, could it be that I would be better solely on T3? If so, any ideas how I get this over to her? She did inform me that I was the only person she had ever prescribed T3 for, and this was because I went to see a private endo. I Have emailed him my test results but am not sure how long he will take to get back to me (I haven't seen him for a while - his suggestion because of cost).

Best wishes


I don't know if it will help re: T3 only but in Dr Anthony Toft's book "Understanding Thyroid Disorders" (available at some pharmacists and not that pricy) he mentions for a minority of patients they may only feel symptomatic relief when TSH is suppressed which is fine as long as FreeT3 is not out of range. It's relating to T4 only as its written but sounds applicable to T3 only or T4/T3 therapy too seeing as the main concern expressed is not with TSH but with FreeT3 being normal as a more important indicator of thyroid state. Hopefully your GP would respect his opinion as he was president of the British Thyroid Association for a number of years and doctor to the Queen in Scotland too.


Thanks Hansaplatz. I have this book somewhere. I will did it out.

Best wishes



FREE T3 LAB TEST: T3 is the active thyroid hormone. Free in front of the T3 means you are measuring what is available and unbound. Those on an optimal amount of desiccated thyroid, with no lingering hypothyroid symptoms and in the presence of healthy adrenals, tend to have a free T3 at the top of the range.

If you are on desiccated thyroid (especially if lower than 3 grains) and find yourself with the free T3 high or above range in the presence of continuing hypothyroid symptoms, or even hyper-like symptoms (anxiety, shakiness), it’s a clue you have adrenal fatigue, aka low cortisol

If not on thyroid medication: 1) If your free T3 is high, you could have Hashimoto’s disease, which will need the two antibodies tests to discern it, or Graves disease, which needs the TSI test. 2) if your free T3 is mid-range or lower, and in the presence of hypothyroid symptoms, you may have hypothyroidism, no matter how low the TSH.

You should NOT take any T3-containing product on the morning of a test.


If your GP requests more thyroid blood tests, make sure she writes on the form that you take T3 and then the lab should explain that that would cause a low TSH reading.

This is because the body is getting the hormone it needs and hence the TSH is not going to produce it.


Thanks Muffy. I doubt she will request any more blood tests as I have only just had them done (21 May). Do you know of any links that explain that taking T3 causes a low TSH please so I can print off and show her? Also, I am not sure how to proceed now with my medication. She is going to have a 'fit' about my low TSH and I'm not sure of the way forward for me with regard to T4 and T3. I feel as if I need more T3, not less, but she is probably going to tell me I am taking too much and to reduce it, or stop it altogether.


She can reduce the T4, as that will help and for your next blood test, you could always leave 36hours before your blood test and the last T3 medication that you take.

I'll try to get back to you with the references. I have them somewhere.


Thank you so much Muffy - this is a great help.


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