If you have symptoms that seem to point to a thyroid gland that is working too quickly, tests can be performed. A blood sample is taken and an ultrasound of the thyroid gland or a radioactive uptake test with iodine or technetium can be performed (a test that makes the functioning thyroid gland tissue visible).
A blood sample is taken from a blood vessel in your arm or hand (vene puncture) to see how much free T4, T3 and TSH is present. With Graves' disease, free T4 is too high and TSH is low. The TSI autoantibody levels are clearly increased, and the antibodies against TPO are normal or increased.
With an ultrasound of the throat, you can clearly see the structure and size of the thyroid gland. When you have Graves' disease, there are no nodules on the thyroid gland.
For a radioactive uptake test, a small amount of labeled iodine (I-123) or technetium will be introduced into your bloodstream via an IV. After that, a series of images (a scintigram) will be made at various moments. These images show to what extent the thyroid gland takes up the labeled iodine or technetium. In Graves' disease, the entire thyroid gland takes up increased quantities of iodine or technetium.