Thyroid UK
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Grave's disease but Underactive??

Hi guys, sorry if I sound a bit stupid but I am very confused now.

Can I be underactive and have graves disease in the same time? I thought Grave's disease is associated with overactive thyrod and not underactive. I think GP said my antibodies were really high (600 if I remember right from his computer screen).

I have just had 2 blood tests in the last 2 weeks both for underactive thyroid. TSH is on higher range (4.9), T4 is 19.4 which I was told is fine. GP raised my levothyroxine from 75mg to 100 and ordered another blood test in 2 months time.

Can someone help me understand what is going on now? :)

Thank you!

6 Replies

Hi you could go underactive if you are on meds such as carbimazole to slow down thyroid production and the dose is too high or you are on block and replace and need more levothyroxine.You could go underactive if you have had RAI treatment, or your thyroid removed and not on enough levothyroxine replacement. Are any of those relevant? X


I am on levothyroxine and did not have RAI treatment or my thyroid removed. When I was diagnosed 11 years ago, my TSH level was 180+, FT4 was too high as well 72 and my FT3 was 1. Appearantly I am a bit of a 'mixed bag' because when you have underactive thyroid your TSH is hight but your T4 is low.


Oh this sounds like one for the experts on here and I only know the basics .When I was diagnosed with Graves my TSH was not there at all and my T4 was high.As you say from what I have read on here yes with underactive the TSH is high side andT4 low side.I have seen posts about not converting T4 to T3 which looking at your T3 of 1 on ddiagnosis alongside a high T4 it does look like that is also happening.I have also heard it that you can have antibodies for Graves and Hashimotos together! Sorry not much help but Clutter or someone will know! Good luck x


Which antibodies did he do?

Your TSH is high. Too high for you to feel well. You need the range for that FT4, and you need an FT3 to know what's really going on. Never take your doctor's word for your results. 'Fine' isn't a diagnosis! You need a printout of the results to know exactly what's what. Always ask for a print-out!

And that retest should be in six weeks time, not two months. Only two weeks difference, I know, but when you're feeling ill, two weeks is a loooooong time!

Hugs Grey


Hello Grey,

yes, I know my TSH is high (4.9), that's why GP raised levo from 75mcg to 100 and asked for a blood test in 2 months time. I went in 3 weeks ago and asked for a blood test because I was feeling more tired and had less energy than usual. Turned out my TSH has been on the high level for over a year but previous GP didn't do anything about it. Fingers crossed the new doc will be better.

I have asked for a full print out but the practice wanted to charnge me £10.00 for it so I asked the GP to print it off for me but only have FT4, TSH, Cholesterol and Haemaglobin results on it. He did say that my antibodies was really high 600 (if I remember right) which means I have Graves disease.

The only thing I don't understand is how I can be underactive and have Graves disease in the same time? Will ask next time I see him if I cannot get an anwer here.


Um, well, it dépends which antibodies you have. They could have been Hashi's antibodies. And as you have a high TSH they are much more likely to be Hashi's than Graves. Did he say you have Graves?


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