Part of “CHAPTER 33 – THYROID FUNCTION TESTS“

Patients with autoimmune thyroid disease commonly develop antibodies to thyroid antigens. Thyroid microsomal antibodies frequently are present in patients with chronic lymphocytic thyroiditis, and Tg antibodies develop in a few patients. Passive hemagglutination tests have often been used clinically. In such tests, sheep erythrocytes are coated with either thyroid microsomal proteins or Tg. These cells are exposed to serial dilutions of serum, and the presence of antibodies is indicated by observing hemagglutination in the test tube. These antibodies may also be detected by several other techniques, including immunofluorescence, complement fixation, EIA, IRMA, and RIA (see Chap. 46). Antithyroid peroxidase antibody measurements are more sensitive and specific for autoimmune thyroid disease30 and are replacing microsomal antibody determinations.