Are Silent Thyroiditis and Postpartum Silent Thyroiditis Forms of Chronic Thyroiditis or Different (New) Forms of Viral Thyroiditis?

Abstract

Subacute (granulomatous) thyroiditis has been regarded as a distinct clinical entity with characteristic histologic findings since the reports of Mygind and De Quervain which appeared near the turn of the century. The 1950 report of Crile and Rumsey1 is noteworthy because of the clear description of the variable clinical aspects of the disease, from the typical acute presentation to the less clinically overt form, which they designated chronic to indicate the ease with which the diagnosis may be missed. Many patients have hyperthyroidism with low 24-h radioactive iodine uptake (RAIU) which resolves spontaneously in several weeks. This is caused by a discharge of stored thyroid hormone occurring when the inflammatory process produces disruption of the thyroid follicles. As the disease resolves there is commonly a phase of hypothyroidism lasting for about 1 month. Within 3 to 6 months recovery is usually complete. Only a small proportion are left with goiter and even fewer have permanent hypothyrodism. In 10% of the patients the disease is unilateral initially.2 It may then spread over a few weeks to involve the rest of the gland.3,4