Method for Measuring Fibroblast Growth Factor-23 and Reagent Therefor

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

• (1) reacting, in an aqueous medium, FGF-23 in a sample with a magnetic particle, a first antibody or a fragment thereof which binds to FGF-23, and a second antibody or a fragment thereof which binds to FGF-23, to form on the magnetic particle an immunocomplex comprising the first antibody or a fragment thereof which binds to FGF-23, FGF-23, and the second antibody or a fragment thereof which binds to FGF-23,
• (a) wherein the sample comprises FGF-23 in a concentration ranging from 5 pg/mL to 10,000 pg/mL when subjected to the reaction, and/or
• (b) the sample comprising FGF-23 in a concentration ranging from 5 pg/mL to 10,000 pg/mL is directly subjected to the reaction;
• (2) collecting the magnetic particle in the reaction mixture after step (1) by magnetic force,
• and separating the magnetic particle collected by magnetic force from the other components;
• and
• (3) measuring the immunocomplex on the magnetic particle separated in step (2).

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

• (1) reacting, in an aqueous medium, FGF-23 in a sample with a magnetic particle, a first antibody or a fragment thereof which binds to FGF-23, and a second antibody or a fragment thereof which binds to FGF-23, to form on the magnetic particle an immunocomplex comprising the first antibody or a fragment thereof which binds to FGF-23, FGF-23, and the second antibody or a fragment thereof which binds to FGF-23, wherein the sample comprises FGF-23 in a concentration ranging from 5 pg/mL to 10,000 pg/mL;
• (2) collecting the magnetic particle in the reaction mixture after step (1) by magnetic force,
• and separating the magnetic particle collected by magnetic force from the other components;
• (3) measuring the immunocomplex on the magnetic particle separated in step (2);
• and
• (4) determining a concentration of FGF-23 in the sample by comparing a measured value obtained in (c) with a calibration curve prepared using known concentrations of FGF-23 ranging from 5 pg/mL to 10,000 pg/mL.