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Thyroid UK
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T3 only consecuences?

Hi. I'm Hypothyroid and suffer pain in my knees (this is the result of the thyroid medication) and palps. I take 1/2 grain of Naturethroid. My blood test says my free t3, free t4 and tsh are in range.

I suspect that taking t4 makes me sick and want to try t3 only, but I'm afraid. What will happen if my t3 stays in range but my t4 drops out of range?

Thank you

5 Replies


Having results within range isn't necessarily sufficient. It's important to know where in range the results are. TSH high in range, FT4 and FT3 low in range mean you are under medicated. If you post your results and ranges members will advise.

If you take T3 only your FT4 will drop as a consequence. If FT3 is high enough in range it won't matter.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


Thank you for answering. This are my blood tests:

Free T3: 3,63 pg/ml (1,80-4,80)

Free t4:1,07 ng/100ml (0,93-1,71)

TSH: 3,09 mcU/ml (0,27-4,20)

I'm taking 1/2 grain of Naturethroid. I used to take levo. I'm better with Naturethroid but my knees still hurt and have palpitations. I want to try T3 only. What will happen if my T4 drops out of range?

Thank you!


As Clutter said, if you take T3 only your Free T4 will drop very low indeed. But, for most people, if you have enough T3 it might not matter about the lack of T4.

Some people do brilliantly on T3 only. Some people feel better with at least some T4 in their bodies.

Personally, I spent about a year on T3 only and did well for most of that time, but eventually I found the lack of T4 did catch up with me, and I started feeling hypo. Raising my dose of T3 didn't help. So since then I have switched to various combos of NDT and T3. I'm currently taking mostly NDT, with only 1/4 tablet T3 at bedtime.

I have no regrets about spending a year on T3 only. For much of that time I felt fairly well.


I understand 100%. T3 is the only way that I can keep my blood panels perfect and not suffer from horrendous joint pain. Cynomel was my saving grace and now need to find and alternative. PCP will NOT prescribe.


Thank you for your response!

I took levo for 12 years but my knees hurt so much so I stopped taking it for 6 months. My knees recovered! but my tsh was so high and palpitations started. Then I started taking Naturethroid and the palpitations got better but my knees started hurting again. Want to give a go to T3 only. Maybe my knees get better and palpitations don't appear. Don't know what to do.


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