Natural course of juvenile autoimmune thyroiditis.

Forty-six patients with juvenile autoimmune thyroiditis were followed for an average of 6.5 years. The diagnosis was based on a firm goiter and on cytologic findings of lymphocytic thyroiditis. The thyroid function and the size of the thyroid gland were regularly evaluated, and thyroid cytologic findings reevaluated once about 4.5 years after the diagnosis was made. Initially, 24 patients were euthyroid, 16 subclinically hypothyroid, and six hypothyroid. At the end of follow-up, 29 patients were euthyroid, six subclinically hypothyroid, and 11 hypothyroid, but there had been an extensive exchange of individual patients among these three groups. At cytologic reevaluation, the changes were virtually unaltered. Thyroid antibodies and circulating immune complexes were repeatedly tested: on one or more occasions, 85% of the patients had positive test results for thyroid antibodies, and about 50% for circulating immune complexes. Hypothyroidism at the end of follow-up correlated with the initial hypothyroid state and with thyroglobulin antibodies of IgG class detected by enzyme immunoassay. The best predictors of the final hypothyroid state were female sex, initial hypothyroidism, IgG thyroglobulin antibodies by EIA, and IgG circulating immune complexes assayed by conglutinin-binding test-EIA.