Sonographic Decreased Echogenicity of Thyroid Parenchyma in Asymptomatic Population: Correlation with Thyroid Function and Thyroid Autoimmune Activity

Abstract

Purpose The aim of the study was to evaluate the correlation between decreased echogenicity of thyroid and thyroid hormones or autoantibodies. Materials and Methods From January 2009 to December 2011, 543 patients with decreased parenchymal echogenicity [M:F = 133:410, median age: 42 years (range: 9–82 years)], who did not have solid nodule, symptom or medication related to thyroid and underwent thyroid function test were retrospectively reviewed. Images were classified based on the degree of hypoechogenicity, heterogenicity or thyroid size. 1) Group A: mild decreased echogenicity, group B: marked decreased echogenicity, 2) group Ho: homogeneous echogenicity, group He: heterogeneous echogenicity, 3) group 1: decreased size, group 2: normal size, group 3: increased size. Differences in triiodiothyronyne (T3), free-thyroxine (fT4), thyrotropin (TSH), anti-thyroglobulin antibody (TgAb), thyroid peroxidase antibody (TPOAb), and anti-TSH receptor antibody (TSH-rAb) were evaluated among groups. Results T3, fT4, and TSH levels differed between groups A and B (p < 0.001, p = 0.001, p < 0.001). TgAb and TPOAb of group B were higher than group A (p = 0.006, p < 0.001). TPOAb of group He was higher than group Ho (p < 0.001). TSH-rAb and TPOAb of group 3 were higher than group 2 (p = 0.017, p < 0.001). Conclusion The patients with findings of markedly decreased, heterogeneous echogenicity or thyroid enlargement may have abnormal thyroid function and autoantibodies. These may facilitate the physicians' decision to order tests for thyroid function and autoimmune activity.

Keywords

• thyroid gland
• ultrasonography
• thyroid hormones
• autoantibodies