**Note: All laboratory testing requires an authorizing physician. DHA Laboratory offers a patient direct program that partners you with an authorizing physician. If you have any additional questions regarding the availability of testing, please contact our laboratory by telephone or email.**
The Thyroid Stimulating Immunoglobulin test measures the level of thyroid-stimulating immunoglobulin (TSI) in your blood. High levels of TSI in the blood can indicate the presence of Graves’ disease, which is an autoimmune disorder that affects the thyroid gland. TSI is a form of immunoglobulin G (IgG) that can bind to thyrotropin (TSH) receptors on the thyroid gland. TSIs mimic the action of TSH, causing excess secretion of thyroxine and triiodothyronine.