Appearance of anti-TSH receptor antibodies and clinical Graves' disease after radioiodine therapy for hyperfunctioning thyroid adenoma

Radioiodine treatment use is frequent in patients with benign hyperfunctioning thyroid diseases and the side-effects are rare. In this paper we described the appearance of TSH-receptor antibodies and the concomitant development of persistent hyperthyroidism in a patient with hyperfunctioning thyroid adenoma after I-131 treatment. A 70-year-old man presented a hyperfunctioning thyroid adenoma with suppressed uptake in the adjacent normal gland. Antibodies against the thyroglobulin (TgAb), thyroid peroxidase (TPOAb) and TSH-receptor (TRAb) were absent. One year after remission by radioiodine therapy the patient developed severe and persistent hyperthyroidism associated with diffuse I-131 uptake in the gland. TgAb and TPOAb remained absent, but TRAb were present. Although spontaneous development of Graves' disease cannot be excluded, the time sequence and the negative familial and personal history for autoimmune diseases suggest a possible connection between the two phenomena. The release of TSH-receptor antigen from follicular cells damaged by I-131 may have triggered the autoimmune response turning a toxic nodular goiter patient into a Graves' disease patient.