Chronic thyroiditis with painful tender thyroid enlargement and transient thyrotoxicosis.

Clinical and laboratory findings and long term outcome (1.5-9 yr) in 7 women and 1 man with chronic thyroiditis (CT) who had painful tender thyroid enlargement were evaluated and compared with those in 11 women with subacute thyroiditis (SAT). Histological features consistent with SAT were not demonstrable, and various forms of CT (fibrous variant, diffuse, or focal lymphocytic thyroiditis) were observed. There were no differences in mean age, duration of symptoms, erythrocyte sedimentation rate, and C-reactive protein values in the 2 diseases. Seven patients had a history of goiter, and none had a history of a preceding upper respiratory tract infection. The mean white blood cell count was significantly lower in CT than in SAT patients. Six CT patients had transient thyrotoxicosis with a marked depression of radioactive iodine uptake. Mean serum T4 and T3 levels and T3 to T4 ratio in these 6 patients did not differ from those in the SAT patients. Five (all with high antimicrosomal antibody titers) of 8 CT patients developed persistent hypothyroidism. In contrast, none of the SAT patients became permanently hypothyroid. TSH binding inhibitory immunoglobulins and thyroid stimulation-blocking antibody at recent examination were negative in these 5 patients. Patients with this disorder present with transient thyrotoxicosis, with a marked depression of the thyroid radioactive iodine uptake, and often develop goitrous or atropic persistent hypothyroidism. This disorder may represent acute exacerbation of an underlying immunological process during the course of CT. To differentiate this syndrome from SAT, thyroid biopsy is necessary.