The clinical significance of immunological markers of diffuse toxic goiter

The clinical significance of measuring thyroid antibodies has been evaluated. With this aim in view, 47 patients with diffuse toxic goiter (DTG) (46 women and 1 man) aged 15 to 65 were examined. Antibodies to TTH receptors were detected in 85 patients with decompensated DTG by the radioligand method based on assessment of blocking of TTH binding to its receptor in the presence of patient’s serum. Antibodies to thyroglobulin (TG) were detected in 55.6% patients before therapy. Blood level of TG was increased in 42% of patients. Antibodies to the microsomal fraction (MS) were detected in 59% of patients. The activity of antibodies to TTH receptor depended on the disease severity, degree of the thyroid enlargement, and size of goiter. The incidence of antibodies to TG and their titers did not depend on the severity of thyrotoxicosis or size of goiter. The incidence of antibodies to MS increased only with enlargement of goiter. The incidence and titers of antibodies gradually decreased in the course of mercasolyl therapy of DTG. After 6 months antibodies to TTH receptors were found in 57% of patients, their activity being decreased, too. The incidence of anti-MS antibodies dropped to 45%, whereas the rate of detection of antibodies to TG was virtually the same. One year after therapy antibodies to TTH receptors were found in 29.4%> of patients. The rate of detection of antibodies to TG and MS decreased to 25 and 20%o, respectively. Hence, a high rate of detection of antireceptor antibodies in DTG and the relationship between the thyroid status and the titer of these antibodies confirm their leading role in the pathogenesis of the disease. The presence of antibodies to TG and MS in no more than half of the patients with DTG and absence of a clear-cut correlations between these antibodies and various clinical hormonal parameters of the disease indicates their significance solely as markers of the autoimmune process in the thyroid but does not specify the nature of its involvement. Antibodies to TTH receptors are the most informative immunological test for the diagnosis of DTG and the markers of immunological remission of the disease.

Thyroid glands in patients with Graves' disease are sources of thyrotropin-binding inhibitory (TBI) activity

In order to investigate the main sources of production of Graves' immunoglobulins, 4 women with Graves' hyperthyroidism, which relapsed after withdrawal of methimazole (MMI) therapy, were selected for this study. The patients underwent subtotal thyroidectomy after pre-operative treatment with MMI and Lugol's solution. Seven blood samples were obtained in each patient during surgery from: 1) a peripheral vein, immediately before neck incision; 2) the carotid artery; 3) and 4) the left and right inferior thyroid veins, respectively, before manipulation of the thyroid; 5) and 6) the left and right inferior thyroid veins, respectively, after surgical handling of the gland; 7) a peripheral vein at the end of operation. Thyrotropin-binding inhibitory (TBI) activity was measured in all samples by a radioligand method. Serum TSH was also measured in those samples. There was a substantial increment of TBI in the thyroid veins compared with the activity in the carotid artery. The mean TBI was significantly higher after surgical handling of the thyroid lobes. The two lobes from each gland secreted differing levels of TBI, whereas the TSH concentrations were similar in all samples from each individual patients. We conclude that at least part of the TBI activity in patients with Graves' disease comes from the lymphocytic infiltration of the glands, and that differences in antibody production between the thyroid lobes may explain the difference in TBI activity in their respective thyroid veins.