Thyroid Iodine Content and Serum Thyroglobulin: Cues to the Natural History of Destruction-Induced Thyroiditis*

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Abstract
Twenty-eight patients with destructive thyroiditis were followed to study the natural history of healing of thyroid gland injury. All had sequential measurements of thyroidal iodine [127I] content by fluorescent scanning (normal mean, 10.1 mg), 17 had serial serum thyroglobulin (Tg) measurements (normal,127I content and Tg levels persisted for 2 or more yr in someindividuals. No patient had detectable Tg antibodies by hemagglutination, but low titers were detected intermittently by sensitive RIA in 5 PTT patients. Microsomal antibodies were positive in only 1 of 16 SAT patients, but in 4 of 7 PTT patients and in both PPT patients. Three patients had positive perchlorate discharge tests (2 of 8 with SAT, 0 of 4 with PTT, and 1 of 1 with PPT). Permanent hypothyroidism occurred in 3 patients (2 with PTT; 1 with SAT and positive antibodies), but did not correlate with perchlorate results. HLA typing and serum immunoglobulin measurements were not useful for predicting the clinical course. These data indicate that several years may be necessary for complete resolution of destructive thyroiditis; many patients have evidence of thyroid injury persisting long after serum thyroid hormone and TSH levels become normal.(J Clin Endocrinol Meta62: 1213, 1986)