Does T4 have any value, other than being converted into T3?

My latest Blue Horizon results are:-

TSH 0.04(0.27 - 4.2)

Free Throxine 5.5(12-22)

Free T3 4.1(3.1 - 6.8)

The comment is that it may be acceptable if I am taking T3 but I might want to discuss with my doctor.

I currently take 50 Levo and 25 T3. I feel much better than when on T4 only but still not as well as I want to!

Not sure if I should increase one or both of my meds. Can anyone help please?

Many thanks


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14 Replies

  • Jenny,

    T3 can suppress TSH and FT4 so those results aren't anything to worry about. Your FT3 is still low in range, though. How long have you been taking T3?

  • Thanks. I have been taking T3 for about 8 months. I tried to increase but it seemed to affect my heart rate and anxiety. I wonder if I should try to increase T4. What do you think?


  • Did you split the T3 when you increased the dose? If you did, then try increasing the T4 by 25mcg and see whether your symptoms improve.

    You also need to make sure that your ferritin is between 70-90 and your vitamin D, B12 and folate are high in range. Hypo-like symptoms can be experienced when the vits and minerals are low or deficient.

  • No I didn't split it, maybe that work better. I think I will try the T4 first it is just too confusing! Where is a good doctor when you need one??

    Thanks. Jx

  • Some drs are okay on the theory but it really takes other thyroid sufferers to *know* thyroid problems and still everyone is differently affected.

    If you increase your T3 in future try taking the extra 6/8 hours after your first dose.

  • Thanks - will do.


  • if increasing T3 affects the heart then check adrenal function, ferretin and D. It may be pooling or not getting into the cells and causing hyperstimulation.

  • If it was me, I think I'd try raising my thyroxine. I don't have a sound, sensible, scientific basis for saying that, just that you say raising your T3 makes you jittery. 50mcg is a low dose of thyroxine, so there's probably room to raise. You'll know fairly quickly if it's helping or making things worse, I would think.

  • Thanks - I think I will try that.


  • My instinct is that T4 is important, not just for its conversion to T3 and I say this because I'm poorly if I try to take T3 only.

  • Thanks - I think that might be what I am wondering. I know some people do well on T3 only but as we always say everyone is different!


  • This is a daft question but if our body doesn't need T4 and so it converts it to T3. Then how can you feel ill on T3 only because that's what a normal thyroid would convert it to. Sorry if im being thick.

  • I don't think your being thick mandy, this has always had me puzzled too.

  • Mandy,

    I think it's likely most people do need FT4. Even though there may be impaired conversion to FT3 some is still being produced even when T3 supplementation is required.

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