title: One-step, labeled-antibody assay for measuring free thyroxin. II. Performance in a multicenter trial.
abstract: The technical and diagnostic performance of a labeled antibody radioassay for free thyroxin (Amerlex-MAB* FT4) was examined in a multicenter trial. The overall mean within-assay precision (CV) in eight centers was 6.2% at 30 pmol/L and 3.6% at 13 pmol/L concentrations of FT4. Between-assay precision was 5.4% at 18 pmol/L and 6.8% at 50 pmol/L. The euthyroid central 95% reference range for FT4 was 11.3 to 24.3 pmol/L. Results of the method correlated well with those of an analog radioimmunoassay: [Amerlex-MAB* FT4] = 1.09 [Amerlex-M FT4] + 1.50 pmol/L (r = 0.96, n = 732). Clinical performance of the assay was better than that of first-generation analog tracer assays for sera from patients with nonthyroidal illness or binding-protein abnormalities.
authors.affiliation: Amerlite Diagnostics Ltd., Cardiff Laboratories, Whitchurch, U.K.
authors.forename: C P
authors.initials: CP
authors.lastname: Sheehan
authors.forename: N D
authors.initials: ND
authors.lastname: Christofides
mesh_terms: D001323:Autoantibodies / Q000097:blood; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood; D007037:Hypothyroidism / Q000097:blood; D011247:Pregnancy; D011863:Radioimmunoassay / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D012016:Reference Values; D013974:Thyroxine / Q000097:blood* / Q000276:immunology / Q000627:therapeutic use; D013975:Thyroxine-Binding Proteins / Q000378:metabolism; D014284:Triiodothyronine / Q000276:immunology
chemical_list: D001323:Autoantibodies; D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine; D013974:Thyroxine