Cut off value of technetium uptake in the differential diagnosis of Graves, disease and subacute thyroiditis

Objective(s):The aim of this study was to determine whether technetium (99mTc) uptake is a relevant method for the differential diagnosis of Graves disease and subacute thyroiditis and calculate its cutoff value in case of its relevancy. Methods: A total of 69 patients, who were followed up (>3 months) in our hospital for thyrotoxicosis within 2015-2019 were enrolled in the study. Out of these 69 subjects, 39 patients had been diagnosed with Graves disease, and 30 of them had subacute thyroiditis. Biochemical parameters, thyroid scintigraphy, and 99mTc uptake test results were evaluated. Results: 99mTc uptake was significantly higher in the patients with Graves disease than in the patients with subacute thyroiditis (P<0.001). Based on the ROC analysis the 99mTc uptake cutoff value of 1.55% had an accuracy of 92.9%, with the sensitivity and specificity of 92% and 87%, respectively. Conclusion:In conclusion, the results of our study suggested that 99mTc uptake test could be used in the differential diagnosis of Graves disease and subacute thyroiditis. The cutoff value of 1.55% for 99mTc uptake test may guide in establishing a differential diagnosis between the two diseases.