Methods for the assay of troponin I and T and complexes of troponin I and T and selection of antibodies for use in immunoassays

A method of increasing assay sensitivity in a cardiac troponin immunoassay, comprising:

• contacting an agent to reduce non-specific adsorption of cardiac troponin I in a body fluid sample obtained from a human subject to a substrate of an assay device, wherein said immunoassay uses antibodies, comprising;
• (a) a first antibody that specifically binds to uncomplexed cardiac troponin I, wherein said first antibody also specifically binds to cardiac troponin I complexed to troponin T and troponin C;
• or
• (b) another first antibody that specifically binds to cardiac troponin I, uncomplexed to either troponin T or troponin C and a second antibody that specifically binds to cardiac Troponin I, complexed to troponin T and troponin C;
• or
• (c) a combination thereof;
• and wherein said immunoassay is configured to provide assay results that are within a factor of two for
• (i) cardiac troponin I, uncomplexed to either troponin T or troponin C, at a concentration between 1 and 15 ng/ml;
• and
• (ii) an equivalent concentration of cardiac troponin I in a complex with troponin T and troponin C;
• and
• wherein said agent that reduces non-specific adsorption increases assay sensitivity for troponin I;
• and
• performing said immunoassay in the presence of said agent, thereby increasing assay sensitivity for troponin I in a cardiac troponin assay.