Subacute thyroiditis is a self-limiting disease that is sometimes managed effectively with steroid administration. Relapse is not
always avoided, however, on cessation of steroid therapy. The main problem in the management of subacute thyroiditis is the absence of guideines for reducing dosage and terminating steroid therapy. High-resolution ultrasonography, a convenient method of imaging the diseased thyroid, may be able to provide these guidelines. We observed the clinical course of subacute
thyroiditis through ultrasonographic images, and classified them into four stages based on their patterns. Decision of treatment procedure was based on these stages. The 12 patients in the control group received conventional treatment; treatment of the other 14 patients was based on ultrasonographic classification. Stage 1, the initial and most severe phase of inflanmmation, consists of thyroid swelling and large hypoechoic areas lacking clear margins. In this stage, 20 to 30 mg of prednisolone was
administered. Stages 2 and 3, the phase of relatively improved inflammation, is characterized by localized hypoechoic changes.
Dose of steroid was decreased 5 to 15 mg after each stage, and steroid administration was ceased once the condition reached stage 4, the recovery phase, which is characterized by almost normal ultrasonographic findings. Relapse rate was 58% in the controls, 14% in the classified groups; the management periods were 133.2 days and 71.3 days, respectively. Management based on ultrasonographic findings can decrease relapse rate and shorten clinical course of subacute thyroiditis. Our data speak
for the clinical usefulness of using ultrasonography in staging treatment of subacute thyroiditis.