How reliable is tsi in determining grave's disease?

TSH?: The TSH is an excellent screen for hyperthyroidism and hypothyroidism.

Not at all perfect: Thyroid stimulating immunoglobulin (tsi) is theoretically the cause of graves disease, which is an autoimmune disease. These antibodies stimulate the thyroid to make excess hormone. However, the test is not perfect. Many people with graves have a negative test for tsi. Some assays are not reliable. Tsi can be measured when the diagnosis is uncertain, but a negative test does not rule out graves.