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Painless thyroiditis may be followed by recurrent hyperthyroidism in patients with Graves’ disease

(March 2004)

The background of the study. Thyroid inflammation may cause or be caused by autoimmune thyroid disease. In this study, patients with painless thyroiditis were followed to determine if their thyroid inflammation led to the onset or recurrence of hyperthyroidism caused by Graves’ disease.

How the study was done. The study group consisted of 92 patients with painless thyroiditis (transient hyperthyroidism and thyroid enlargement, with a low thyroid radioiodine uptake). Forty of them had a history of Graves’ hyperthyroidism and were in remission after prolonged antithyroid drug therapy; they had onset of painless thyroiditis 4 to 122 months after the therapy was stopped. The other 52 patients with painless thyroiditis had no history of Graves’ disease. All the patients were followed for at least six months after the onset of painless thyroiditis.

The results of the study. Seven of the 40 patients (18 percent) who had a history of Graves’ hyperthyroidism had recurrent hyperthyroidism 8 to 10 weeks after the onset of painless thyroiditis. At the onset of painless thyroiditis, these seven patients had more thyrotropin (TSH)-receptor antibodies in their serum than did the 33 patients who did not have recurrent hyperthyroidism. No patient in the group who had no history of Graves’ hyperthyroidism had the onset of hyperthyroidism during follow-up.

The conclusions of the study. Patients with Graves’ hyperthyroidism in remission after being treated with an antithyroid drug may have a recurrence of hyperthyroidism after an episode of painless thyroiditis.

The original article. Iitaka M, Morgenthaler NG, Momotani N, Nagata A, Ishikawa N, Ito K, Katayama S, Ito K. Stimulation of thyroid-stimulating hormone (TSH) receptor antibody production following painless thyroiditis. Clin Endocrinol (Oxf) 2004;60:49-53.