[Comparative studies on the clinical accuracy of two "competitive-binding-assays" for the determination of effective serum thyroxine].

160 sera of patients with normal or disturbed thyroid function was tested by ETR (Byk-Mallinckrodt) and Quantisorb (Abbott) for their metabolically effective thyroxine concentration. In 124 cases the in vitro findings were correlated with extensive clinical data, which had permitted to establish a definite judgement of thyroid function. 5,5--13,5 mug% were considered as normal values with Quantisorb, 0,8--1,18 (see article) with ETR. A critical evaluation of the test results showed a better distinction between normal and abnormal thyroid function with Quantisorb, which explains also the higher diagnostic accuracy of this kit (92,75% : 85,5%). "Grey-zones" between normal and abnormal thyroid function were found with both tests, they were smaller, however, with Quantisorb than with ETR. The Quantisorb kit can therefore be recommended for routine function tests in vitro, although the slightly greater laboratory work should be considered.