My Husband was diagnosed with graves disease , was on carbimazole for a couple of years, which was successfully keeping his TSH within normal levels, but then suddenly wasn t. He took the radioactive iodine tablet in June this year, then he had a very low TSH so upped his medication again (after stopping for the treatment) then suddenly from one month to the next, his TSH level went from very low to very high, indicating a serious level of hypothyroidism . He saw his specialist, who said to reduce the amount of carbimazole he was on from 20mg per day, to 15mg per day. He feels terrible. It has been a month now since his last blood test, and if his TSH remains so high, would it not be wise to remove the Carbimazole altogether? Why would the specialist not suggest stopping that drug immediately?