Comparison of two triiodothyronine uptake techniques for the assessment of thyroid function

The present study was designed to compare the Thyopac and Triosorb triiodothyronine uptake tests. A normal range was established for the two procedures. Neither test was affected by iodine-containing drugs or contrast media but abnormal results were obtained during pregnancy and in subjects receiving oestrogens. Both tests proved satisfactory in the diagnosis of hypo- and hyperthyroidism, giving results consistent with clinical assessment and with serum protein-bound iodine determinations. The Thyopac procedure was preferred for a number of reasons. It requires less plasma; it is slightly simpler and quicker and it is not time dependent.