Recurrence and heterogeneity in painless thyrotoxic lymphocytic thyroiditis. Report of five cases.

Five patients had recurrent episodes of spontaneously resolving thyrotoxicosis (SRT). Three displayed only the classic low-intake variety of this disorder, while two had alternating episodes of high-uptake and low-uptake thyrotoxicosis. Two of the three with low uptake only who had thyrotropin displacement activity (TDA) assays had negative results on this test, while one of the patients with alternating high- and low-uptake thyrotoxicosis had a positive TDA assay result, suggesting that the pathogenesis in the two types of SRT may differ.