A COMPARISON OF THE THYROIDAL PLASMAI131CLEARANCE AND THE PLASMA PROTEINBOUNDI131TESTS FOR THE DIAGNOSIS OF HYPERTHYROIDISM

Abstract
Thyroidal plasma I-131 clearance and the 48-96 hour plasma PBI-131 concentration tests were compared with respect to their usefulness for evaluation of thyroidal function. Patients (136) were studied, including a group of 27 patients previously treated by radioiodine or surgery for thyroid disease. Whereas good differentiation between toxic and nontoxic states was obtained with both tests in previously untreated patients, the plasma PBI-131 test was frequently misleading in patients previously treated for thyroid disease.