title: Assay of serum thyroxine by competitive protein binding: reuse of disposable sephadex columns.
abstract: A method for the assay of total serum thyroxine on reusable Sephadex G-25 fine columns, obtained from the Ames Tetralute kit, and competitive protein binding with TBG is described. The columns are regenerated with diluted plasma and may be used for at least 3 months. The procedure is rapid and simple and requires no extraction, centrifugation or evaporation. Recovery of added thyroxine from serum is essentially complete. The between-assay and within-assay coefficients of variation are about 5.5%. Correlation with values obtained using the Tetralute kit was good (r = 0.988). Values in 75 euthyroid subjects were normally distributed and therefore the normal range was taken as the mean +/- 2 SD or 4.6-10.4 mug/100 ml.
mesh_terms: D002850:Chromatography, Gel; D005069:Evaluation Studies as Topic; D006801:Humans; D007700:Kinetics; D011869:Radioligand Assay / Q000379:methods; D013974:Thyroxine / Q000097:blood*; D013975:Thyroxine-Binding Proteins
chemical_list: D013975:Thyroxine-Binding Proteins; D013974:Thyroxine