Abstract: Disclosed is a method by which the adsorption of cystatin C to a container can be inhibited in a simple manner to improve the accuracy of the measurement of cystatin C. Provided are: a cystatin C adsorption inhibitor comprising a non-ionic surfactant; a cystatin C measurement reagent comprising the adsorption inhibitor; and a cystatin C measurement kit. Also provided is a method of inhibiting the adsorption of cystatin C, the method comprising bringing a cystatin C-containing sample into contact with a measurement instrument in the presence of a non-ionic surfactant. The aforementioned non-ionic surfactant is preferably a polyoxyethylene-type surfactant. Alternatively, the aforementioned non-ionic surfactant has preferably a phenoxy structure, more preferably a benzylphenoxy structure.

Abstract: A latex agglutination method by which the measurement range is extended and the sensitivity of the measurement in the low concentration range is increased, is disclosed. The method for measuring a test antigen by latex agglutination uses two types of large and small particles, having different average particle sizes. Each latex particle is sensitized with an antibody which undergoes antigen-antibody reaction with the test antigen. The purity of the antibody immobilized on the latex particles is within a specific range. The ratio of the amount of the antibody immobilized per one small latex particle to the amount of the antibody immobilized per one large latex particle; the average particle size of the large latex particles; the average particle size of the small latex particles; the concentration of the large sensitized latex particles in the antigen-antibody reaction system; and the concentration of the small sensitized latex particles in the reaction system are within a specific range.

Abstract: Disclosed is an agent for inhibiting decrease in measured values in immunoassays, which may reduce the influences by interfering substances in a test sample so as to promote the accuracy of the immunoassays, as well as an immunoassay and a reagent for immunoassays using the same, with which the decrease in the measured values due to the interfering substances is reduced. The agent for inhibiting decrease in measured values in immunoassays, caused by interfering substances, is an ionic surfactant having a molecular weight of 1000 to 100,000, the agent being a polymer in which a hydrophobic cyclic monomer(s) having an ionic functional group(s) is(are) polymerized.

Abstract: Disclosed is a method by which the adsorption of cystatin C to a container can be inhibited in a simple manner to improve the accuracy of the measurement of cystatin C. Provided are: a cystatin C adsorption inhibitor comprising a non-ionic surfactant; a cystatin C measurement reagent comprising the adsorption inhibitor; and a cystatin C measurement kit. Also provided is a method of inhibiting the adsorption of cystatin C, the method comprising bringing a cystatin C-containing sample into contact with a measurement instrument in the presence of a non-ionic surfactant. The aforementioned non-ionic surfactant is preferably a polyoxyethylene-type surfactant. Alternatively, the aforementioned non-ionic surfactant has preferably a phenoxy structure, more preferably a benzylphenoxy structure.

Abstract: A latex agglutination method by which the measurement range is extended and the sensitivity of the measurement in the low concentration range is increased, is disclosed. The method for measuring a test antigen by latex agglutination uses two types of large and small particles, having different average particle sizes. Each latex particle is sensitized with an antibody which undergoes antigen-antibody reaction with the test antigen. The purity of the antibody immobilized on the latex particles is within a specific range. The ratio of the amount of the antibody immobilized per one small latex particle to the amount of the antibody immobilized per one large latex particle; the average particle size of the large latex particles; the average particle size of the small latex particles; the concentration of the large sensitized latex particles in the antigen-antibody reaction system; and the concentration of the small sensitized latex particles in the reaction system are within a specific range.

Abstract: A latex agglutination method by which the measurement range is extended and the sensitivity of the measurement in the low concentration range is increased, is disclosed. The method for measuring a test antigen by latex agglutination uses two types of large and small particles, having different average particle sizes. Each latex particle is sensitized with an antibody which undergoes antigen-antibody reaction with the test antigen. The purity of the antibody immobilized on the latex particles is within a specific range. The ratio of the amount of the antibody immobilized per one small latex particle to the amount of the antibody immobilized per one large latex particle; the average particle size of the large latex particles; the average particle size of the small latex particles; the concentration of the large sensitized latex particles in the antigen-antibody reaction system; and the concentration of the small sensitized latex particles in the reaction system are within a specific range.

Abstract: A measurement value lowering inhibitor for immunoassay method that is capable of enhancing the accuracy of immunoassay method through suppressing of any influences of interfering substances existing in an analyte sample; and using the inhibitor, an immunoassay method in which any measurement value lowering by interfering substances is suppressed and a reagent for immunoassay method. The measurement value lowering inhibitor for immunoassay method used to suppress any measurement value lowering by interfering substances is comprised of an ionic surfactant consisting of a polymer obtained by polymerization of a hydrophobic cyclic monomer having an ionic functional group, which has a molecular weight of 1000 to 10×104.

Abstract: A latex agglutination method by which the measurement range is extended and the sensitivity of the measurement in the low concentration range is increased, is disclosed. The method for measuring a test antigen by latex agglutination uses two types of large and small particles, having different average particle sizes. Each latex particle is sensitized with an antibody which undergoes antigen-antibody reaction with the test antigen. The purity of the antibody immobilized on the latex particles is within a specific range. The ratio of the amount of the antibody immobilized per one small latex particle to the amount of the antibody immobilized per one large latex particle; the average particle size of the large latex particles; the average particle size of the small latex particles; the concentration of the large sensitized latex particles in the antigen-antibody reaction system; and the concentration of the small sensitized latex particles in the reaction system are within a specific range.