Abstract: A method of assaying bone collagen degradation activity in a human subject. In the method, a human urine sample is reacted with an antibody which (i) is capable of reacting immunospecifically with pyridinium crosslinks selected from the group consisting of native free pyridinoline and native free deoxypyridinoline, and (ii) has a ratio of reactivity toward the selected pyridinium crosslinks and urinary pyridinium peptides larger than 1,000 daltons in molecular weight, of greater than about 5:1. An immunocomplex forms between the antibody reagent and the selected pyridinium crosslinks which are present in the sample, and the amount of immunocomplex is measured. Also disclosed are antibody reagents and kits which can be used in the method.

Abstract: A method of assaying a human urine sample, by measuring a concentration of pyridinium crosslinks from which the concentration of total hydrolysed pyridinoline in the sample can be determined, is disclosed. In the method, a urine sample is reacted with an anti-Pyd antibody reagent which preferably has a ratio of reactivity toward native free pyridinoline and urinary pyridinoline peptides larger than 1,000 daltons in molecular weight, of greater than 10:1. By measuring the extent of immunocomplex formed by the reaction, the concentration of total hydrolysed pyridinoline in the sample can be calculated. Also disclosed are an antibody reagent and kit which can be used in the method.