Thyroid stimulating immunoglobulin (TSI)

View the Hyperthyroidism Slideshow Pictures

Medical Definition of Thyroid stimulating immunoglobulin (TSI)

Thyroid stimulating immunoglobulin (TSI): 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. The TSI level is abnormally high in persons with hyperthyroidism due to Graves' disease.


Quick GuideHyperthyroidism Symptoms and Treatment

Hyperthyroidism Symptoms and Treatment

Subscribe to MedicineNet's General Health Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Reviewed on 5/13/2016

Health Solutions From Our Sponsors