Painless Thyroiditis as a Cause of Hyperthyroidism

In the past three years, reports of 39 patients (17 male, 22 female) with an unconventional form of thyroiditis who had signs and symptoms of hyperthyroidism, low to absent thyroidal uptake of radioactive iodine ( 131 I) and no history of thyroidal pain and/or tenderness have appeared in the literature 1-7 and in this issue of theArchives(p 45). This form of hyperthyroidism has accounted for 3.6% 6 to 16% 7 of all cases of thyrotoxicosis and for 29% of thyroiditis. 6 Although this virtual epidemic of reports suggests a new disease entity, 8 painless thyroiditis has been recognized for the past 20 years. 9 The hyperthyroidism may be mild or very severe. The thyroid gland is nontender, firm, and (usually but not always 7 ) mildly to moderately enlarged. As expected, exophthalmus is absent, but the eye signs associated with increased sympathetic tone may be present. The hyperthyroid phase lasts