Fig. 1

Receiver operating characteristic analysis of TSH alone as compared to ITA-PSV and TSH to predict increase in LT4 ≥ 50 μg. The AUC (0.905) value of ITA-PSV and TSH for predicting an increase in LT4 ≥ 50 μg was higher as compared to that of TSH alone (0.743), though the difference was not significant (p = 0.123). Abbreviations: AUC, area under the curve; TSH, thyroid stimulating hormone; ITA-PSV, inferior thyroid artery peak systolic velocity; LT4, levothyroxine