Scintigraphic features of autoimmune thyroiditis.

The term autoimmune thyroiditis encompasses multiple inflammatory conditions of the thyroid gland, each with variable clinical manifestations. The more acute forms, silent (painless) thyroiditis and postpartum thyroiditis, are associated with transient hyperthyroidism and are sometimes mistaken for Graves disease. The chronic form, Hashimoto thyroiditis (chronic autoimmune thyroiditis), results in goiter and eventual hypothyroidism unless it is recognized and treated promptly. Thyroid uptake measurements and scintigraphic findings (usually obtained with technetium-99m or iodine-123) play a complementary role along with thyroid function testing in differentiating autoimmune thyroiditis from other thyroid diseases, thereby influencing treatment. In some cases, histologic evaluation of biopsy specimens is required to yield the definitive diagnosis. Knowledge of the entire spectrum of these disorders is essential for appropriate case management.