What are the antibody tests for Hyperthyroidism (Graves' disease)?

Hyperthyroidism antibody tests are essential diagnostic tools that help identify the cause of overactive thyroid function. The most important antibody tests include thyroid stimulating immunoglobulin (TSI), thyroid peroxidase antibody (TPOAb), and thyroid receptor antibody (TRAb). These tests should be ordered when symptoms of hyperthyroidism are present, such as unexplained weight loss, rapid heartbeat, anxiety, tremors, or heat intolerance. TSI and TRAb are particularly useful for diagnosing Graves' disease, the most common cause of hyperthyroidism, as they detect antibodies that mimic thyroid stimulating hormone and activate thyroid receptors. TPOAb helps identify autoimmune thyroid conditions like Hashimoto's thyroiditis, which can sometimes cause transient hyperthyroidism. These tests require a simple blood draw and results typically return within a few days. Normal ranges vary by laboratory, but elevated antibody levels generally indicate an autoimmune cause of hyperthyroidism. The results help guide treatment decisions between medication (methimazole or propylthiouracil), radioactive iodine therapy, or surgery. Antibody levels may also be monitored during treatment to assess disease activity and response to therapy.