Thyroid UK
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Ft4 going lower

I had my bloods done in December my Tsh 0.03 (0.35-5.5) my ft4 was 14.6 (10.5-22.5) ft3 4.6 (3.5-6.5) I was on 150mcg of thyroxine Gp said I needed to reduce so he reduced my my dose to 125mcg had retake of bloods and my Tsh was 0.9 same ranges as above but as my ft4 was only 14.5 gp agreed to put it back up as I was feeling symptomatic on 125mcg. Hair falling out,aching joints etc

But now I am back up to 150mcg but still don't feel great and my last results showed Tsh was 0.09(0.35-5.5) but my ft4 is low in range at 11.6.

In short can't understand why my ft4 is so low when my tsh is nigh on suppressed sorry if it doesn't 't make any sense.

3 Replies

You could do with taking more thyroxine to get your T4 levels up. I take 100mcg thyroxine and 20mcg liothyroinine but my T4 has dropped from 21 to 15. T3 is 5.1, so to get my T4 levels up I have increased to 125mcg, then will go to 150 or 175 and see if this makes a difference. Also, I am increasing my T3 by 20mcg to get T3 to upper third of the range. Gp does not agree with this though, and wants to reduced thyroxine to 75 as my TSH levels are undetectable. My gp practise only look at TSH which is totally ridiculous. I had better gp's in the past who looked at T4 and T3. I am under an endo, who wants to reduce thyroxine also, but who specialises in diabetes not thyroid, so have asked to be referred to another one instead. Look up Dr A Toft, and also have a read of Dr Skinners book, it can be borrowed from thyroid uk. I bought my own copy and its one of the best. I turned to self-medicating as gp wont prescribe the amounts I need.

1 like

VanessaB, 150mcg is considered to be a suppressive dose but your TSH isn't suppressed which is <0.04. FT4 doesn't respond as quickly as TSH to dose changes so your FT4 may take a little longer to recover. Scroll down to Guidelines and Treatment Options to read Dr. A. Toft's comments to Pulse Magazine

Email if you want a copy of the article to show your GP.

Ask your GP to test ferritin, vitamin D, B12 and folate as hypothyroid patients are often deficient/low and these deficiencies can cause musculoskeletal pain, fatigue and low mood similar to hypothyroid symptoms. Good ferritin levels are required for optimal absorption of Levothyroxine and good vitD levels for conversion of T4 to T3. Post your results with the lab ref ranges in a new question and members will advise whether supplementation is required.


NEVER let your doctor lower your meds, you can do it yourself if you think you need to but once the doctor lowers it you will have hells' own game to get them to raise it again should you need it!! Blood tests mean very little, once you are on any form of thyroxine your TSH can be suppressed so I would take back control if I were you and monitor myself based on how I felt not on numbers!


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