Subacute thyroiditis

For sixty-five years subacute thyroiditis has had an uncertain place in the classification of thyroiditis. Recent studies justify the conclusion that this unique type of thyroiditis is not an autoimmune disease, and a consistent serologic connection with any one group of viruses has not been demonstrated. No epidemiologic pattern has emerged to imply person-to-person contagion despite frequent epidemics. The pathophysiology of the disease must be considered in relation to the stage of the process and the frequent history of recurrences which can cause prolonged illness. It is likely that the characteristic clinical and laboratory manifestations are due to direct injury to the thyroid rather than an indirect effect upon the pituitary gland, and the results of laboratory tests do not always parallel the severity of the illness. Treatment with aspirin and thyroid hormone or corticosteroids is symptomatically effective but does not alter the clinical or histologic progress of the disease. Two cases of permanent myxedema resulting from subacute thyroiditis have been well documented in the literature, and true hyperthyroidism does occur, although it is not as well documented. No mortality is associated with this self limiting disease, but long-lasting debility occasionally occurs.