Performance of five thyroid-function tests by radioimmunoassays with antibodies attached to paramagnetic micro-particles.

We have assessed the analytical and clinical performance of five thyroid-function tests by commercially available radioimmunoassays in which antibodies attached to paramagnetic micro-particles are used (Corning MAGIC assays). We evaluated the methods for measuring thyroxin, triiodothyronine, triiodothyronine uptake, thyrotropin (thyroid-stimulating hormone), and free thyroxin. Precision, patients' results, and clinical correlation of the MAGIC assays were similar to those of the well-established RIAs used as the comparative methods in this study; the MAGIC assays, however, are much faster and easier to perform.