US findings in euthyroid patients with positive antithyroid autoantibody tests compared to normal and hypothyroid cases.

PURPOSE

We aimed to compare the ultrasonographic and laboratory parameters of euthyroid patients who have only positive antithyroid autoantibody test results with those of patients with a hypothyroid status of Hashimoto's thyroiditis (HT).

MATERIALS AND METHODS

Thirty-five patients with newly diagnosed HT, 35 euthyroid patients who have autoantibodies against thyroid peroxidase (TPOAb) and/or thyroglobulin (TgAb), and 40 controls were enrolled in the study. Plasma free T3, free T4, thyroid stimulating hormone, TPOAb, and TgAb levels were obtained retrospectively. For gray-scale ultrasonography, each thyroid gland of all individuals graded with gray-scale grading (GSG), which was determined according to the gland size, parenchymal structure, echogenicity, micronodulation, contour irregularity, and existence of hyperechoic septa. For Doppler analysis, the peak systolic velocity (S), resistive index (RI), and pulsatility index (PI) values were obtained from the superior thyroid artery (STA) and intrathyroidal artery (ITA). The color pixel ratio (CPR), which was computationally evaluated from a power Doppler image of all individuals, was used for quantification of the intrathyroidal vascularity.

RESULTS

Although the mean GSG values were higher in the HT and antibody-positive groups than they were in the control group, there was no significant difference between the HT and antibody-positive groups. The three study groups demonstrated no statistically significant difference with regard to the S, RI, or PI variables obtained from the STAs and ITAs. Although the CPR values were highest in the HT group, the difference between the HT and antibody-positive group did not reach statistical significance.

CONCLUSION

The euthyroid antibody-positive group revealed gray-scale and Doppler ultrasonographic findings that were similar to those of the HT group.