A material which is used to verify the performance of an assay intended to be used for the qualitative and/or quantitative detection of antibodies to the thyroid gland and/or specific products of thyroid gland metabolism in a clinical specimen. Assayed antibodies include autoantibodies directed at antigens such as thyroid gland tissue, thyroglobulin, and thyroid peroxidase (TPO) [known as anti-microsomal antibody].