Use of color Doppler ultrasound to differentiate Graves’ disease from silent thyroiditis in patients treated at Fundación Valle del Lili in 2022-2024

Background: Graves' disease (GD) and silent thyroiditis (ST) are common etiologies of thyrotoxicosis requiring optimal diagnosis to provide different therapeutic approach. Here we compare the diagnostic performance of color Doppler thyroid ultrasound (CDU) with measurement of thyroid artery systolic velocities, thyroid scintigraphy with Tc99 and anti-thyroid-stimulating hormone receptor antibodies (TRABs) to differentiate GD from ST in a tertiary center in Cali, Colombia, between 2022-2024. Methods: This single-center prospective study included 78 adult patients diagnosed with thyrotoxicosis between January 2022 and October 2024. Participants had available information on medical records, thyroid function tests, thyroid peroxidase antibodies, TRABs, CDU and, thyroid scintigraphy at the time of diagnosis. Data analysis was performed in October 2024 and determined area under the curve, sensitivity, and specificity of CDU and scintigraphy for differentiating GD from ST, and the performance of each measured parameter were determined. Results: 78 patients were included, 63% were diagnosed with Graves' disease, and 37% with thyroiditis. 28/29 patients with thyroiditis (96.6%) had superior thyroid artery systolic velocities (STV) < 43 cm/s and 25/29 of cases (86.2%) had thyroid tissue blood flow (TBF) < 14.1%. The presence of a diffusely increased pattern + percentage of trapping higher than 4.9% in scintigraphy had a sensitivity of 80% and a specificity of 90% for the diagnosis of GD. Conclusions: CDU of the thyroid arteries with measurement of systolic velocities is a useful diagnostic tool for differentiating between GD and ST. A cut-off point of STV < 43 cm/s has a high positive predictive value for ST diagnosis.