Abstract: The present invention provides an immunological detection method for trimeric type I collagen N-terminal propeptide in a biological sample, which uses a first antibody that binds to a specific portion of a pro-?1 chain in the trimeric type I collagen N-terminal propeptide and a second antibody that binds to a specific portion of a pro-?2 chain in the trimeric type I collagen N-terminal propeptide. The immunological detection method is easy to handle and can specifically (selectively) measure the trimer in biological samples containing the trimer and monomer of the ?-chain of PINP.

Abstract: The problem addressed by the present invention is to provide an immunological assay method using a monoclonal antibody and a kit including the monoclonal antibody, which can be used for assaying ICTP without requiring special facilities. This problem can be solved by a method for immunological assay of type I collagen C-terminal telopeptide in a biological sample, including contacting type I collagen C-terminal telopeptide with a monoclonal antibody that recognizes an amino acid sequence represented by GFDFSFLP (SEQ ID NO: 1) as an epitope.