Endocrine Abstracts

Objective: To compare the roles of inferior thyroid artery (ITA) peak systolic and end-diastolic velocities (PSV and EDV) measured by color flow Doppler ultrasonography (CFDUSG), TSH receptor antibody (TRAb) measured by M22 based ELISA and Tc-99m pertechnetate uptake for differential diagnosis between Graves’ disease (GD) and silent thyroiditis (ST).

Methods: One hundred and fifty previously untreated subjects with GD (111 female, 39 male, mean age 38.4±12.8 yeras), 79 with ST (58 female, 21 male, mean age 39.2±14.1 years) and 71 healthy euthyroid controls (43 female, 28 male, mean age 35.8±10.5 years)were included in the study. The diagnosis of GD and ST were made according to the patient’s signs and symptoms, physical examination findings, the results of TRAb and Tc-99m pertechnetate uptake and follow-up findings. All subjects underwent CFDUSG for the quantitative measurement of ITA blood flow velocities.

Results: The mean ITA-PSV and EDV in patients with GD were significantly higher than those with ST (59.0±24.6, 25.2±11.2, 21.4±5.3 and 9.8±2.9 cm/s respectively, P<0.0001 for both comparisons). However, the mean ITA-PSV and EDV were also significantly higher in subjects with ST than controls (21.4±5.3, 9.8±2.9, 17.2±4.4 and 7.6±2.3 cm/s respectively, P<0.0001 for both comparisons). In ROC analysis the sensitivity/specificity of the 30 and 13.2 cm/s cutoff values of the mean ITA-PSV and EDV for discrimination of GD from ST were 95.3/94.9 and 89.3/88.6% respectively. The sensitivity/specificity of the 1.0 IU/l and 3% cutoff values of the TRAb and Tc-99m pertechnetate uptake were 93.0/91.0 and 90.7/89.9% respectively.

Conclusion: This study suggests that the measurement of ITA-PSV by CFDUSG is a usefull diagnostic tool for differential diagnosis between GD and ST. In ROC analysis the sensitivity and specificity of the most appropriate cutoff value of the ITA-PSV were higher than the sensitivity and specificity of the the most appropriate cutoff values of TRAb and Tc-99m pertechnetate uptake.