RT Journal Article SR Electronic T1 Improved Method for the Measurement of Serum Thyroxine JF Journal of Nuclear Medicine Technology JO J. Nucl. Med. Technol. FD Society of Nuclear Medicine SP 34 OP 37 VO 4 IS 1 A1 Brown, Mary Lou A1 Hannah, Therian C. YR 1976 UL http://tech.snmjournals.org/content/4/1/34.abstract AB Methodology for the measurement of thyroxine in unextracted human serum is described. Antibodies were prepared by immunization of rabbits with thyroxine-human serum albumin (T4-HSA) conjugates. Bound and free labeled hormones are separated using the double antibody technique. The validity of the assay has been demonstrated by the excellent recovery of exogenous T4 added to various serum samples and by production of a curve obtained by various dilutions of a hyperthyroid serum which is parallel to the standard curve. Radioimmunoassay T4 values ranged from 4.5 to 12.0 μg/100 ml in 172 euthyroid patients. In all clinical states, serum T4 values obtained by radioimmunoassay afforded excellent agreement (correlation coefficient, 0.95) with those obtained by competitive protein binding assay. Advantages of the method over commercially available radioimmunoassay kits or the competitive protein binding assay are outlined.