Subacute thyroiditis (SAT), also called subacute granulomatous or de Quervain thyroiditis, is a spontaneously remitting, painful, inflammatory disease of the thyroid gland, which is considered the most common cause of painful thyroiditis. It is an uncommon but important cause of fever of unknown origin (FUO). SAT is often preceded by an upper respiratory tract infection and occurs concurrently with outbreaks of viral diseases (mumps, measles, influenza). However, the exact etiology is unknown. Clinically, it presents with acute onset of pain in the thyroid region. The pain may be exacerbated by turning the head or swallowing, and may radiate to the jaw, ear or chest. Common initial clinical features include low-grade fever, fatigue, and mild thyrotoxic manifestations. The physical examination, an elevated erythrocyte sedimentation rate, an elevated thyroglobulin level, and a depressed radioactive iodine uptake confirm the diagnosis. Therapy with antithyroid drugs is not indicated in patients with SAT because this disorder is caused by the release of preformed thyroid hormone rather than synthesis of new T3 and T4. Therapy with beta blockers may be indicated for the symptomatic treatment of thyrotoxicosis. Nonsteroidal anti-inflammatory drugs are generally effective in reducing thyroid pain in patients with mild cases. Patients with more severe disease require a tapering dosage of prednisone given over two to four weeks.
