method for measuring freitestosteronen in biological fluids

摘要

A method for measuring the concentration of a free ligand in a biological fluid in the presence of bound ligand and endogenous binding proteins, without disturbing the equilibrium between free ligand and protein-bound ligand, which comprises (a) incubating a sample of biological fluid with (i) a ligand analog tracer which due to its chemical structure, does not bind to some of the endogenous binding proteins but does bind to at least one other endogenous binder protein, (ii) a specific ligand binder and (iii) at least one specific chemical inhibitor reagent that singly or in combination inhibit the binding of the ligand analog tracer to said at least one other endogenous binding protein; (b) separating the ligand analog tracer bound to the specific binder from unbound tracer; and (c) determining the concentration of free ligand in said biological fluid.