Measurement method for fibroblast growth factor-23 by forming immunocomplexes

A method for measuring fibroblast growth factor-23 (FGF-23) in a sample, which comprises the steps of:

• (1) reacting in a first aqueous medium, a sample and a first antibody produced by FERM BP-7838 hybridoma or an antibody fragment thereof which binds to FGF-23 to produce Immunocomplex 1 consisting of FGF-23 and the first antibody or the antibody fragment thereof which binds to FGF-23;
• (2) reacting in a second aqueous medium, a second antibody produced by FERM BP-7839 hybridoma or an antibody fragment thereof which binds to FGF-23 with Immunocomplex 1 produced in the aforementioned step (1) to produce Immunocomplex 2 consisting of the first antibody or the antibody fragment thereof which binds to FGF-23, FGF-23, and the second antibody or the antibody fragment thereof which binds to FGF-23;
• and
• (3) measuring Immunocomplex 2 produced in the aforementioned step (2);
• wherein
• the first aqueous medium comprises at least one type of surfactant selected from the group consisting of NONION E-230, NONION K-220, PLONON 208, and NEWCOL 740, or
• the first aqueous medium comprises at least one type of surfactant selected from the group consisting of NONION E-230, NONION K-220, PLONON 208, and NEWCOL 740 and the second aqueous medium is the same as first aqueous medium.