Wednesday, July 27, 2016
I´m a 30 year old woman. I had Graves untill 3 years ago, but 5 months ago the TSH was 0.42. Then last month it was 3.65. Both of the times the fT3 and fT4 were almost the same, about 4.2 and 17.5. Do the changes in TSH mean anything? My question is: Is there a pattern that happens before the thyroid fails?
Graves' disease is caused by antibodies that stimulate the thyroid. No one knows why the immune system makes these antibodies. Usually the immune system makes them continuously, but sometimes it sort of turns the antibody production on and off. I think that is what is happening in your case. Each time the TSH is low, your immune system is making antibodies that are stimulating the thyroid. However, the fact that the free T4 and free T3 are normal indicates that this stimulation is very mild. The bottom line is that you are at risk for your Graves' disease returning again. At this point there isn't anything to do except get blood tests regularly and watch out for symptoms of an overactive thyroid.
I am assuming that you are not taking thyroid hormone pills. Taking too much thyroid hormone would cause a low TSH, and changes in the dose of the thyroid hormone pill could cause changes in the TSH up and down.
Thomas A Murphy, MD, FACP, FACE
Associate Professor of Medicine
School of Medicine
Case Western Reserve University