TSHR and hyperthyroidism: Hyperthyroidism from thyroid stimulators other than TSH: Graves’ disease (GD) is the most common cause of hyperthyroidism which is an autoimmune syndrome resulting from the production of thyroid stimulating antibodies (TSAbs), sometimes called TSHR Ab capable of stimulating thyroidal TSHRs, resulting in excessive TH production and release, and overstimulation of gland growth.