Thyroid Stimulating Immunoglobulins (TSI)

Thyroid Stimulating Immunoglobulins (TSI) are antibodies produced by the immune system that mistakenly target the thyroid gland. They mimic the action of the hormone-releasing signals from the brain, overstimulating the thyroid. This leads to increased thyroid hormone production, causing hyperthyroidism, as seen in Graves' disease. TSI levels can be measured through blood tests to help diagnose this condition. Essentially, TSIs are immune proteins that cause the thyroid to become overactive, leading to symptoms like rapid heartbeat, weight loss, and irritability.