Thyroid Antibodies Decoded: Which to Order, When They Matter, and When They Don't
Thyroid Antibodies Decoded: Which to Order, When They Matter, and When They Don't Three antibodies, three different clinical stories—and the autoimmune crossover that ties them to everything else you're managing. Thyroid antibody testing is one of the most commonly ordered—and most commonly misinterpreted—panels in primary care. Every week I see providers ordering the full antibody panel on every patient with an abnormal TSH, or panicking about a positive anti-TPO in someone with a perfectly normal thyroid. Let's sort out what each antibody actually tells you and when it changes your management. The Three Thyroid Antibodies Anti-TPO (Thyroid Peroxidase Antibody) Target: Thyroid Peroxidase Enzyme The workhorse antibody for Hashimoto's thyroiditis. TPO is the enzyme that catalyzes thyroid hormone synthesis. Anti-TPO antibodies activate complement and are directly involved in thyroid tissue destruction. Present in ~95% of Hashimoto's patients and ~70% of Graves'...