Test results on thyroxine only - any comments?

I would be very grateful for any comments on these test results. As background, I have stopped taking combination T4/T3 on advice of endocrinologist due to heart arhythmia. Now just taking 100mg thyroxine (previously took 110 thyroxine and 10 mg liothyronine). I note that although my TSH is low, Free T4 is in range, but Free T3, although in range, is at lower end. A previous test in my former regime had Free T3 in higher range (but suppressed TSH). I read somewhere that people on thyroid replacement do better when free T3 is in higher ranges. Wonder if I should reduce the Thyroxine and re-introduce T3 into my treatment (assuming I can now get it)?.

TSH 0.07 (normal range 1.27-4.20)

Free T4 20.28 (normal range 12-22)

Free T3 3.94 (normal range 3.1-6.8)


I have posted results to endo and will see what he says.

9 Replies

  • You'd feel better, I believe if FT3 was towards the top of the range. Did you leave 24 hours between your last dose of levo and the test and have the earliest appointment, fasting (you can drink water)?

    I'd wait to see what Endo suggests but I know in the UK, T3 has been withdrawn.

  • Thanks. No I took my morning dose, and did the self blood test about midday.

    I have been feeling cold and finding concentration difficult.

  • You should allow 24 hours approx between last dose of thyroid hormone and the test as not doing so can skew the results too.

  • Yoiur FT4/FT3 ratio on T4 only is more than 5. This indicates poor conversion, and the fact you can only just scrape into the bottom tof the FT3 range when the FT4 is high in its range supports this. Pay no attention to the TSH. If you are a poor converter then you need so much T4 to make even a modicum of T3 that you will suppress TSH. In your case TSH isn't a useful pointer at all.

  • Thanks, that's interesting. Would it be useful to have the gene test for T4:T3 conversion do you think?

    I felt okay on the T4/T3 combo for years until I went into atrial fibrillation.

  • Diogenes is a scientist, doctor and adviser to Thyroiduk, so I'd certainly take his excellent advice

  • I wouldn't bother about the genetics: stick to curing the problem however you can! Did you have regular FT3 measured during your years of combo? If not, you could have been overdosed either continually or sometimes without knowing it. There is an FT3 level right for you; the problem is finding it.

  • I felt okay on the T4/T3 combo for years until I went into atrial fibrillation.

    You might have been better with less T4 and more T3 rather than having the T4 reduced and the T3 taken away altogether. Arrhythmia can happen with too little T3 as well as too much.

    An experiment that you could have tried is to have split your T3 into 2 doses and taken it at different times, just to see what happens.

    Another point - Nutrients...

    Low iron can cause tachycardia and arrhythmia. Low B12 can have serious affects on the heart. Basically, being low in any nutrients can have bad effects on the heart. You should ask for your ferritin, iron, vitamin B12, vitamin D and folate to be tested. Make sure you get the results and the reference ranges and post them on here, then ask for feedback. Just being in range isn't enough. They have to be optimal.

  • Thanks for useful comments. I split the T3 dose into two, morning and afternoon. Had tests in July 2016:

    Vitamin B 12 : 561 (range 180-2000)

    Serum Folate: 4.8 (range 2.8-20)

    Ferritin: 111 (range 20 - 300)

    In July 2015 Vitamin D was 61, also had a blood count, not sure which one is iron.

    Have been taking some general supplements since january 2016 - multivitamin/mineral (Biocare), vitamin D, Vitamin C, Essential fatty acids.

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