THE VALUE OF ULTRASONOGRAPHY IN THE DIAGNOSIS AND FOLLOW-UP OF SUBACUTE THYROIDITIS

Twenty-three consecutive patients with clinical and biochemical suspic ion of subacute thyroiditis (SAT) were evaluated by ultrasonic scannin g of the thyroid. Ultrasonic findings supported the diagnosis in all c ases. In the 16 patients in whom thyroid scintigraphy was performed th is was compatible with SAT. Initially, median thyroid volume was 40 mL (range 20-289) and a very low echogenicity was demonstrated in all pa tients. The extension of hypoechogenicity exceeded 75% in the majority of patients. Thyroid volume was significantly reduced to a median of 13 mL (range 9-40) (68% reduction, P < 0.00001) at a median follow-up period of 18 months (range 6-33) and a majority of the patients (60%) had persistent morphological abnormalities. No correlation between thy roid function and the extension of hypoechogenicity initially or at en d of follow-up could be demonstrated. Recurrence was noted in 8 patien ts (35%), two of whom were positive for anti-TPO antibodies, but the r isk of recurrence could not be correlated to the extension of hypoecho genicity or initial thyroid function. Recurrence was related to the fu rther extention of hypoechoic areas and increase in thyroid volume, as evidenced by ultrasonography in our series. None developed thyroid an tibodies, and all were euthyroid at the end of the observation period. We believe that high resolution ultrasonography has a useful supporti ng role in the diagnosis of subacute thyroiditis. In case of doubt and differential diagnostic considerations, it facilitates guided biopsie s. Additionally, it allows determination of disease activity and thyro id size.