Thyroid UK
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Blood test help please?

Hi I'm hoping someone can offer advice, I had my bloods results on friday, I have hyperthyroidism and my bloods 4 weeks ago were: (I am on 30mg Carbimazole a day)

Free T4 35.5 (7-17)

TSH was 0.02 (0.35-5.50)

2 weeks ago they were:

Free T4 26.5 (7-17)

TSH 0.02

Friday's results are:

Free T4 10.5 (7-17)

TSH 0.02.

My GP wants me to continue taking 30mg carbimazole a day and the GP and I think this is mad, I told her I would surely become underactive if I continue but she disagreed, I'm not seeing Endo for another 5 weeks... what would you do? Thank you

5 Replies

The Carbimazole is working fast which is good news. You could do as your GP says (stay on same dose) but do another blood test in 2 weeks to see if it has gone too low. Or you could try and reduce a bit to 20 mg/day and do another blood test before you see the endo - you will have to tell them how you have adjusted the dose.


Thank you for your reply. Yes it has worked fast, I just don't won't to go underactive, I have reduced to 10mg I hope this won't push levels further down. I have been waiting to see endo since beginning of Feb, I will feel better under their care.


Just be aware that your levels may go over again if you reduced too fast. Another blood test before you see the endo is a good idea.


I had a similar thing happen when I was on a higher dose of Carbimazole and the doctor actually phoned me at work to tell me I was going hypo and to reduce the medication immediately.

I felt a while back I should reduce again but now my results are looking wonderful and really stable, having changed the dose down with the doctor's advice and maintaining this for about 8 months now. The results went low then rose again to a near perfect T4 and my TSH level is on the move to a much better score.

How about calling the endro's office and asking for advice, mentioning it's a few weeks until the next appointment and would it be okay to reduce and take a blood test a few days before your appointment so he/she can see reduced rate results? Worth a call as the biggest lesson I have learned from this journey is taking control of my decisions but with advice from the experts so I can do so in safety.

1 like

Hi thank you for your reply. That's what I'm worried about as it's going towards the lower end of normal and my GP isn't concerned at all, I have decided to only take 10mg and will see what my bloods do in two weeks. I haven't had my first appointment with the endo yet so I'm not sure if I can call to ask about it. I will be trying to see a different GP this week if I get an appt that is! Should I not be on block and replace method by now that is what I've read but I don't know enough about this thing!


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