A Comparison Between Two Imaging Techniques for the Diagnosis of Subacute Thyroiditis (De Quervain Thyroiditis) Brief Communication

Purpose: Subacute thyroiditis (SAT) or de Quervain thyroiditis is a relatively frequent and self-limited condition with a triphasic clinical course. Its symptoms can mimic other thyroid, upper respiratory, and ear infections. Thyroid ultrasonography (TUS), radioactive iodine uptake (RAIU), and thyroid scintigraphy (TS) may be used for differential diagnosis. To assess and compare the diagnostic value of thyroid TUS and TS in patients on the first phase of a clinically diagnosed SAT. Material and Methods: Twenty-two patients (18 women and 4 men, age, 37.2 +/- 9.83 years) with clinical diagnosis of SAT were prospectively studied. Thyroid stimulating hormone, T3, free T4, antithyroperoxidase antibodies, thyroglobulin, polymerase chain reaction, complete blood count and differential, TUS, TS, and RAIU at 2 and 24 hours were performed. Results: All patients were on thyrotoxic phase with a thyroid stimulating hormone mean of 0.03 +/- 0.030 mU/L (range: 0.005-0.13); antithyroperoxidase antibodies were positive in 3 patients (>= 75 UI/mL); thyroglobulin was elevated in 16 patients (>= 55 ng/mL). RAIU at 2 hours was 1.94% +/- 0.85% (range: 1%-4%), and at 24 hours, 0.98% +/- 1.24% (range: 0.10%-5%). TS showed low uptake in all patients. On TUS, only 8 patients were compatible with SAT. In 13 patients, TUS was consistent with goiter, diffuse type in 8, multinodular in 5, and normal in 1 patient. Conclusion: Low thyroid scan uptake with I-131 at 2 hours (< 4%) and 24 hours (< 5%), and poor thyroid visualization on TS seem to be more prevalent than focal distortion and heterogeneity in TUS in thyrotoxic phase of SAT.