Measurements by Competitive Binding Radioassay of Serum Anti-Microsomal and Anti-Thyroglobulin Antibodies in Graves' Disease and other Thyroid Disorders1
Using competitive binding radioassay methods, the anti-(thyroid)-microsomal (anti-M) and anti-thyroglobulin (anti-TG) content of sera of patients with Graves' disease and other thyroid disorders have been measured. A very high proportion of sera from 55 patients with previously untreated Graves' disease contained abnormal amounts of these antibodies, 98% and 89%, respectively. None of the untreated patients had normal serum concentrations of both antibodies. These results thus indicate that thyroid autoimmunity is uniformly a concomitant of untreated Graves' disease. Long acting thyroid stimulator (LATS) was detected in the sera of only 38% of the same subjects. There was no correlation in a given serum between any of the 3 IgG globulins with respect to magnitude of the elevation. Abnormal serum concentrations of anti-M and anti-TG were noted in 20% and 23%, respectively, in a group of 111 hospitalized control subjects. In an enlarged control series of 330 patients, 79 (24%) had elevated serum anti-M values. Of the latter group 71% were found to have either thyroid disorders, collagen or autoimmune disease, widespread neoplasms, renal disease, or other endocrine-metabolic disorders. At moderately high serum anti-M levels, 94% of 31 control subjects had one or more of the above cited diseases. These results indicate that the frequency of thyroid autoimmunity in a hospital population may be considerably higher than hitherto appreciated. Following 131I-iodide treatment for Graves' disease, serum anti-M values invariably rose sharply and transiently to about 15× the pre-treatment level; serum anti-TG increased in most subjects to about 10× the pre-treatment level. In contrast to observations on serum LATS, serum anti-M elevations were associated more with thyrotoxicosis per se than with complicating ophthalmopathy or dermopathy, and the frequencies with which elevations of serum anti-M or anti-TG were observed in patients with dermopathy did not differ significantly from those with ophthalmopathy. Anti-M was detected in abnormal amounts in the sera of 95% of 19 patients with chronic thyroiditis, in 75% of 12 patients with hypothyroidism, but only in 1 of 9 subjects (11%) with simple and/or adenomatous goiter.