Silent thyroiditis.

Silent thyroiditis is an increasingly recognized cause of transient thyrotoxicosis. Inflammatory destruction of thyroid follicles results in release of preformed thyroxine and triiodothyronine. Patients present with symptoms of thyrotoxicosis, but unlike subacute thyroiditis, lack thyroid pain or tenderness. The thyrotoxic state spontaneously resolves in 2 to 12 weeks at which time the patient either returns to a euthyroid state or passes through a transient hypothyroid phase. Diagnostic laboratory findings include elevations of thyroxine and triiodothyronine and a markedly depressed radioactive iodine uptake. It is imperative for the primary care physician to distinguish silent thyroiditis from chronic causes of hyperthyroidism, eg, Graves' disease, since treatment must be palliative rather than definitive. Long-term prognosis is usually excellent.