The mixed haemadsorption test as an aid to the diagnosis of thyroid autoimmune disease.

The usefulness of the mixed haemadsorption technique as a diagnostic test for thyroid autoantibodies was evaluated from the results with sera from 389 cases of thyroid disorders, 109 cases of connective tissue disease and 347 apparently healthy persons. A positive result at a titre ≥1:1600 was found to indicate either chronic thyroiditis or thyrotoxicosis with a probability of about 80% and this probability increased with increasing titre. The reactions were of two types, ring zones and filled zones. Ring zones were obtained with about 70% of the sera from cases of chronic thyroiditis, with about 20% of thyrotoxic and thyroid carcinoma sera, with 10% or less of sera from patients with other conditions and with about 5% of healthy female controls. The ring zone reaction was frequently associated with a reaction against thyroid cytoplasmic antigen in the immunofluorescence and complement fixation tests but the antibodies involved were not identical with those detected by the latter two tests. The organ specificity of the reactions obtained in the mixed haemadsorption test was checked by comparison with the reactions obtained on other cell cultures than the thyroid, using the same technique. The incidence of positive thyroid mixed haemadsorption in normal controls was found to vary with age and sex as with other thyroid antibody tests.