The wells of the microtitre strips are coated with purified human Tg Antigens. During the first incubation, specific autoantibodies in diluted serum or plasma bind to the Antigens-coated surface. The wells are then washed to remove unbound components. In the second incubation, the Conjugate, enzymelabelled antibodies to human IgG, binds any surface-bound autoantibodies. After further washing, specific autoantibodies are traced by incubation with the Substrate. Addition of Stop Solution terminates the reaction, resulting in a coloured end-product. The amount of Conjugate bound is measured in absorbance units. In the qualitative protocol, the amount of Conjugate bound by the sample is compared with that bound by the Reference Control. In the quantitative protocol, the concentration of anti-Tg autoantibody can be estimated by interpolation from a dose-response curve based on Standards. The Standards are referenced against the International Reference Preparation of anti-thyroglobulin 65/93. Sample Types: serum, plasma. Range: Cutoff. Time: 2 hours ? Thyroglobulin (Tg), thyroid peroxidase (TPO) and the TSH receptor are considered the major autoAntigenss associated with chronic autoimmune thyroiditis. Clinical diagnosis is usually based on the presence of serum or plasma autoantibodies to Tg and TPO1. In Graves' disease (chronic primary hyperthyroidism), the TSH receptor is the Antigens most directly involved in clinical manifestations of the disease2.