MEASURMENT OF CIRCULATING THYROID MICROSOMAL ANTIBODIES BY THE TANNED RED CELL HAEMAGGLUTINATION TECHNIQUE: ITS USEFULNESS IN THE DIAGNOSIS OF AUTOIMMUNE THYROID DISEASES

Abstract
Thyroid‐microsomal antibodies were quantitated by a new technique utilizing tanned sheep red blood cells coated with human thyroid microsomal antigens. This haemagglutination assay (MCHA) correlated with the immunofluorescent antibody (FAB) but not with the thyroglobulin haemagglutination antibodies (TGHA) assay. Of forth‐one patients with Hasmimoto's thyroiditis, Thirty‐nine (95%) were MCHA but only twenty‐four (59%) TGHA positive. Titres were similar for the hypothyroid and euthyroid patients. Patients less than 20 years of age had either negative (50%) or low titre (less than 1:160) TGHA but 100% positive MCHA at titres greater than 1:1280. Of twenty‐one patients with Graves’diseases eighteen (86%) were MCHA and six (29%) TGHA positive. Of thirty‐two patients without thyroid diseases eleven (34%) were MCHA and/or TGHA positive. On the basis of family history and associated abnormalities, in eight of eleven, positive antibodies may have been due to subclinical Hashimoto's thyroiditis. Fourteen subjects of a control group (10%) were MCHA postivie. Seven of ten examined had goitres. MCHA is a simple and quantitative test, useful in the diagnosis of autoinnune thyroid diseases.