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T3 - Blood Test advice

Hi everyone,

I started a low dose of T3 in July (private prescription). I take 5mcg in the morning and 5mcg in the afternoon. I feel like a new woman! I also take 150mcg of Levo. I had my bloods done last week:

TSH 0.02 (0.27 - 4.20)

Free T4 20.9 (12 - 22)

Free T3 5.4 (3.1 - 6.8)

(I’m pleased that my Free T3 has improved since before it was only 3.9 and Free T4 had been 17.3).

The consultant wants me to see him to discuss dosage. I’m thinking probably a reduction in Levo as I feel that my Free T4 Level is a bit high?

Grateful for sage advice :)

7 Replies

It depends how you feel. Just because your FT4 is near the top of the range, don't adjust the dose if you feel well. I take Levo plus T3 and I feel better when my FT4 is 19.5, not so well when it's lower.

1 like

Thanks Susie. I’m feeling generally much better thanks to the introduction of the T3, but I had been feeling a bit like I had too much T4 as I’ve been prone to a few hot sweats. So I wasn’t too surprised to find out my FT4 was right at the top. The consultant is concerned that the TSH is so low (0.02) but I thought that it would be low due to the meds? Maybe I need to drop a bit of Levo to bring the TSH up a little?



It depends whether lowering Levo will raise your TSH. It doesn't seem to happen with me but I've been on Levo for 40+ years (last 2 years T3 added) and the last time my TSH was in range was 2003. My FT4 plummets if I lower my Levo to try and raise TSH and I feel extremely unwell. But that might not be the case with you.

TSH can lower when adding T3. But at the end of the day what matters is how you feel, where you feel best and the dose that keeps you there. Low TSH isn't a problem according to Dr Toft, leading endocrinologist and past president of the British Thyroid Association, as long as FT3 stays within range. See thyroiduk.org.uk/tuk/about_... > Treatment Options:

According to the BMA's booklet, "Understanding Thyroid Disorders", many people do not feel well unless their levels are at the bottom of the TSH range or below and at the top of the FT4 range or a little above.

The booklet is published by the British Medical Association for patients. Avalable on Amazon and from pharmacies for £4.95 and might be worth buying to highlight the appropriate part and show your doctor.

Also -

Dr Toft states in Pulse Magazine, "The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance.

But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."

You can obtain a copy of the article by emailing louise.roberts@thyroiduk.org print it and highlight question 6 to show your doctor.


It's worth trying a 25 mcg reduction in levothyroxine, you may not need it, but try to negotiate being able to resume it if you need to.

1 like

I think I’ll try that to see how I feel. Was on 150mcg of Levo before starting the T3 and it hasn’t been reduced yet. I understand that T3 is 3 Times as strong as Levo so I reckon I might need to lower the Levo whilst taking T3.


Are you supplementing for your lowish B12, plus vitamin B complex. What about vitamin D, was only average

Do you have Hashimoto's? If so are you gluten free

I would stick on this dose if you feel good. Review at next test

1 like

Vitamins all good on a previous test a few months ago and I do supplement daily. My antibodies were lower than the range so thankfully I’m probably not got Hashis. I’m trialling cutting out as much bread as I can to see if that helps with weight management.


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