Introduction: Thyrotoxicosis due to Graves' disease (GD) and destructive thyroiditis (DT) needs differentiation, as management strategy differs. Factors that help in diagnosis are biochemical and nuclear imaging. Utility of high-resolution ultrasonography (HRUSG) and color Doppler (CD) in differentiation is not widely practiced. We undertook the prospective study in the Department of Endocrine Surgery at a tertiary care center among South Indian population in 1 year as a cost-effective model