Subacute thyroiditis

Abstract

Subacute thyroiditis, also known as Granulomatous thyroiditis, Viral thyroiditis, and de Quervain's thyroiditis, described by Fritz de Quervain in 1905, is an uncommon condition accounting for up to 5% of overall thyroid disorders. It is a self-limiting and remitting inflammatory disease often following an episode of upper respiratory infection. Viral infection provides the antigen either directly or by virus induced host cell damage that binds to HLA molecules on macrophages. The patient usually presents with anterior neck pain that may radiate to the ipsilateral jaw, throat, ears, and rarely mediastinum. Also, the prodrome of fever, fatigue, myalgia, arthralgia, and anorexia precedes 2 weeks before the illness. Thyroid dysfunction presents with the typical triphasic pattern. The initial phase of thyrotoxicosis wherein damage to thyroid follicles releases the preformed hormone followed by the hypothyroid phase and finally resolving euthyroid phase. The hypothyroid phase is predominantly transient, and permanent hypothyroidism can occur in 25% of patients at the end of 2 years. Diagnosis is based on a complete hemogram showing highly elevated ESR, and CRP. A radionuclide uptake scan is a gold standard in differentiating Graves' disease from subacute thyroiditis, which shows very little uptake. Treatment is predominantly conservative and managed with beta blockers. Antithyroid drugs have no role as there is no increase in the production of the hormone. Thyroxine replacement is not needed and the course happens over 3-12 weeks.