Triiodothyronine uptake test in which antibody-coated tubes are used compared to two other tests in which precipitation separations are used.

A triiodothyronine uptake test in which antibody-coated tubes are used (Clinical Assays) was compared to two other such tests in which silicate tablets (Nuclear-Medical Laboratories, Inc.) or macroaggregated albumin (Diagnostic Corporation of America) are used to separate the bound from the free fraction. The Clinical Assays test showed good linear correlation with the values obtained by the other two tests on 67 samples. The interassay coefficient of variation was 4.8%. The correlation between the values obtained and the clinical evaluation on 60 patients also was essentially the same as for the other two tests, 80%.