Re-evaluation of thyroid uptake rate of I-131 as the diagnostic test for hyperthyroidism

To test the validity of Thyroid Uptake Rate of ¹³¹I（TUR）in diagnosing hyperthyroidism,122 patients with confirmed hyperthyroidism and 67 with normal thyroid function,all undergoing TUR and T4 or T3 Suppression Test（TST）were grouped and compared using four criteria:（1）TUR at 2H higher than 31%,at 4H higher than 48% and 74% at 24H;（2）TUR ratio between 2/4H or 4/24H higher than 80 or 85%;（3）the peak TUR occuring before 24H;（4）TUR suppression rate at 24H after T3 or T4 intake lower than 50%.Among those criteria,（1）and（2）had low sensitivity, low specificity thus could not be used to separate the two groups;（3）had high specificity but sensitivity too low to be of practical use;（4）had the highest sensitivty（98.4%）,specificity（85.1%）, positive predictive rate（92.3%）and negative predictive rate（96.6%）.In conclusion,TST appears more reliable than any of the criteria and any combination of the other criteria,thus to be the only choice in term of diagnosing hyperthyroidism with traditional Thyroid Uptake Test.