Thyroid UK
82,950 members97,983 posts

fluctuating t4 when meds are reduced

hi in novemberi was feeling realy tired and sluggish my bloods showed t4 9.00 and tsh 0.96 my doctor said he thought I could be going underactive and reduced my dose of carbimazole from 15mgs to 10 mgs my bloods in dec were t4 13.9 and tsh 0.14 and were creeping up to going overactive again but would not consider a change in dosage until another bold test I asked if it was possible to tweak the dose somewhere inbetween but he was reluctant idont know if this is because there isn,t a smaller doseage between the 10 and 15 mgs worried I might creep up to far so wondered if I can tweak the dose myself say by half a tablet would this be safe as I have a bad case of flu virus at the moment cant have bloods done until I,m clear as antibiotics could affect the readings

3 Replies

with a t4 of 9 no wonder you were tired

your T4 no matter whether overactive or underactive should be in UPPPER quadrant of its range so much nearer 20

sounds to me like your on too much carbimazole

if 10mg is to much can you not split the pills and try 5mg


Frian, your TSH is low, but not suppressed and your FT4 13.9 is still low so you are nowhere near going overactive. Ideally FT4 will be in the top 50-75% of range. I would wait for the next blood test before tweaking your dose, but yes, you can cut a 5mg tablet to achieve 12.5mg.


I cannot see how the doctor is saying you are creeping into overactive, with those levels???

Your T4 would have to be over 20, to be anywhere near going into overactive.

I also don't see why someone would say you tsh is low...thats' not low, that is high, but not a concern at all, it will come down with time and patience.

Your T4 is within the normal range, (12-22) so I would cut your carbimazole in half, or get a 2nd opinion from another doctor.


You may also like...