RESUMO
Objective:To search for the clinical indicators in differentiating Graves′ disease from subacute thyroiditis (SAT).Methods:Retrospective analysis was performed on thyroid function measurement of 265 cases of newly diagnosed Graves′ disease, 76 cases of SAT with thyrotoxicosis, 100 cases of non-toxic thyroid nodules, 105 cases of autoimmune thyroid diseases with normal thyroid function, and 151 cases of outpatients with normal thyroid function and without thyroid diseases.Results:Free triiodothyronine(FT 3)/free thyroxine(FT 4) ratio of Graves′ disease patients was significantly higher than that of SAT patients with thyrotoxicosis (0.65±0.29 vs 0.32±0.75, P<0.05). Receiver operating characteristic curve(ROC curve) analysis of FT 3/FT 4 ratio between Graves′ disease group and SAT group showed that FT 3/FT 4 ratio greater than 0.4 with a sensitivity of 98.11% and a specificity of 83.81% for diagnosis of Graves′ disease. Conclusion:FT 3/FT 4 ratio greater than 0.4 is helpful for differentiating Graves′ disease from subacute thyroiditis with thyrotoxicosis.