SCINTIGRAPHIC FINDINGS OF THE THYROID IN EUTHYROID OPHTHALMIC GRAVES-DISEASE

The scintigraphic findings of the thyroid were analyzed in patients wi th euthyroid ophthalmic Graves'-disease known to have some thyroid-rel ated abnormalities. Methods: Technetium-99m-pertechnetate images of th e thyroid from 38 euthyroid ophthalmic Graves' disease patients with s mall, soft or nonpalpable goiter were analyzed. Results: Scan images s howed homogeneous (even) and nonhomogeneous (uneven) Tc-99m uptake in 20 and 16 patients respectively. Poor images due to low uptake were ob served in two patients. Six patients displayed alterations in scintigr aphic appearance from even to uneven patterns after T3 suppression tes t. Statistical analysis revealed that the uneven pattern was more freq uently observed in euthyroid ophthalmic Graves' disease patients than in 26 patients with hyperthyroid Graves' disease who were euthyroid du ring antithyroid drug therapy (p < 0.005). The scintigraphic heterogen eity was correlated with reduced uptake as well as a higher ratio of t he uptake values after T3 treatment to the pretreatment values. Scinti graphically, hot or warm lesions were observed in most cases showing t he uneven pattern (16/22; 73%). Rather low titers of antithyroglobulin , antimicrosomal antibodies and TSH-binding inhibitor immunoglobulins were detected in only 4 (10.5%), 7 (18.4%) and 12 (31.6%) patients res pectively, while the prevalence of thyroid-stimulating antibodies (TSA b) was as high as 86.8% (33/38). The scintigraphic heterogeneity did n ot correlate with the detection of these antibodies but did correlated with the severity and duration of ophthalmopathy. Conclusions: The pr esence of functioning follicular cells with some autonomy that were he terogeneously distributed in the thyroid was observed in about half th e euthyroid ophthalmic Graves' disease patients. Chronic stimulation b y TSAb may be the underlying mechanism for these findings.