Thyroid UK
84,025 members99,007 posts

T4 toxic....undermedicated or what

i been chatting on another group and someone suggested i may not be converting T4 to T3 so now T4 toxic

because high TSH and palps and all my symptons including forgetting how to do things i been doing easily for a while

im so confused now as if thats the case how can i even suggest it to my dr? ive not had a T4 test and have never had a T3 test let alone anything else

im scared to go back on levo because if i aint converting surley im going to just continue going downhill

allso been suggested undermedicated but that would mean i would have improved when i went from 25 to 50 which i didnt i got worse and worse

im so confused and depressed at the moment just feel like im being let down all the time

6 Replies

On re-reading your question, you say you have never had a T4 or T3 test. Are you talking about your natural T4/T3 that your own body produces? You do not say if you have been diagnosed with hypothyroidism but say you have taken 25mcg and then 50mcg levo.

With a high TSH and palpitations it would seem to me that you are not on enough medication. (although sometimes levo can give palps too).

If you can get a new blood test from your GP (or if you have a recent one get a copy of them from your surgery complete with the ranges) and post them on a new question. Also get a Vitamin B12, Vitamin D, iron, ferritin and folate.

Regarding you thinking you would have improved on going from 25mcg to 50mcg levo - these are usually starting doses and a blood test should have been done about every six weeks with an increase in meds till you felt well - not the GP diagnosing by your TSH only.

Best wishes


was diagnosed in may and put on 25mcg levo

had no symptons only a high TSH and weight gain

after 2 maybe 3 weeks palps started and i feel really ill brain fog body aches chills sweating lack of concentration ect

increased to 50mcg thinking id feel better but got worse and worse

last TSH 5.2 in august

drs wont do another test now until next august/september next year


I see my reply to Butty, just above. If GP not able to do the Free T3 test, common . Then have TSH, T4 and Free T3 done on line. It is essential to have these 3 tests together to know what is happening. Not safe to take Free T3 without a test, You may well need less T4 ( levo) and a littleT3, however, Free T3 must never go over range, so test first vital. Also 6 weeks after any change in meds. t3 needs splitting into 2 doses about 12 hour apart. Also , always build up slowly to the prescribed dose as that way less die effects. Common with T3. Normally starting dose is 10 or 20 mcg per day. It makes a huge difference, if you need it It does lower the TSH.

I use Blue Horizon ,main page for my thyroid tests. Never go through a private hospital, very expensive. They do a finger prick or venous blood. However, both fine and Lab well known. Your GP etc may fill B.H phial full of blood for you. Quote TUK10 for discount £60-£70

Best wishes,



Thankyou Jackie £60-£70 looks much better than some of the prices i seen earlier this morning. I will ask dr to do the tests ill just say i need them done so they can see that there is a problem with me being on levo alone and hope they agree have more joy getting blood out of a stone i think. Hopefully endo agrees to a trial of something today or insists i have a blood test as my dr claims i dont need one until next year


Hi Mandy, My GP like that, have actually said that to her! Water and ducks!

Who ever prescribes the bloods ( 3) are essential for your own safety, especially the heart. It is usually the NHS Labs,, the managers, little Hitlers, who will not do the FT3, costs. Mostly hospital Labs for in/out patients will.Make sure you have all the tests from the Endo.If good, usually automatic.Then phone the sec for results + ranges, unless Endo sends them to you, some do.

Best wishes,



Mandy, poor conversion may be due to deficient cofactors mentioned in this video.

He has many other videos.....all very informative regarding autoimmune thyroid condition.


You may also like...