Thyroxine (T4) Autoantibody Interference of Free T4 Concentration Measurement in a Patient With Hashimoto's Thyroiditis

Dear Editor, Interactions of thyroid hormone autoantibodies (THAAs) with thyroxine (T4) or triiodothyronine (T3) are less common than interactions of antibodies to thyroglobulin, microsomal thyroid peroxidase, and thyroid-stimulating hormone (TSH) receptor. Nevertheless, these THAAs have been reported to cause spurious thyroid function test (TFT) results, indicating that TFT results do not always accurately reflect the clinical status of the patient and are not necessarily consistent [1, 2]. KCI Citation Count: 4