title: A critical evaluation of separation methods in radiommunoassay for total triiodothyronine and thyroxine in unextracted human serum.
abstract: Methods for separating free and antibody-bound hormone in radioimmunoassays for total triiodothyronine (T-3) and thyroxine (T-4) in unextracted human serum are evaluated. For T-3 assay, a simplified second antibody technique has significant advantages over other methods and gives a mean interassay coefficient of variation of 7.2% over a wide range of values. For T-4 assay, polyethylene glycol is the method of choice and has a mean interassay coefficent of variation of 4.7%. By adding the separating agents initially, the assays are readily semi-automated and may be completed within a working day.
mesh_terms: D000704:Analysis of Variance; D005069:Evaluation Studies as Topic; D006801:Humans; D008722:Methods; D011092:Polyethylene Glycols; D011863:Radioimmunoassay; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine; D011092:Polyethylene Glycols; D013974:Thyroxine