Patent ID: 6153440
Filing Date: 2000-11-28
Classification: G01N

Abstract:
An immunoassay method for the simultaneous measurement of free thyroxine (T.sub.4) and free triiodo-L-thyronine (T.sub.3) thyroid hormone concentrations in a serum sample comprising the steps of:(a) dialyzing the serum sample to equilibrium in a physiological buffer system so that the free T.sub.3 and the free T.sub.4 are separated from T.sub.3 and T.sub.4 bound to serum proteins;(b) combining a measured quantity of the dialyzed serum sample having free T.sub.3 and free T.sub.4 with reagents comprising:(i) a measured quantity of T.sub.3 labelled with a detectable marker and a measured quantity of T.sub.4 labelled with a detectable marker;(ii) an anti-T.sub.3 antibody of sufficient specificity and in sufficient quantity to bind a measurable quantity of the free T.sub.3, and an anti-T.sub.4 antibody of sufficient specificity and in sufficient quantity to bind a measurable quantity of the free T.sub.4 ;(c) allowing reaction of the free T.sub.3 and the free T.sub.4 and the labelled T.sub.3 and the labelled T.sub.4, with the anti-T.sub.3 antibody and the anti-T.sub.4 antibody to proceed substantially to equilibrium to thereby produce antibody bound labelled T.sub.3 and antibody bound labelled T.sub.4 ;(d) separating the unbound labelled T.sub.3 from the antibody bound labelled T.sub.3 and the unbound labelled T.sub.4 from the antibody bound labelled T.sub.4 ; and(e) determining the concentrations of T.sub.3 and T.sub.4 in the sample by comparing relative amounts of antibody bound labelled T.sub.3 and T.sub.4 and unbound labelled T.sub.3 and T.sub.4.