Detection of collagen degradation in vivo

In a method of analyzing a body fluid sample for the presence or concentration of an analyte indicative of a physiological condition, comprising the steps of contacting the body fluid sample with an immunological binding partner which binds to the analyte, detecting binding of the immunological binding partner in the body fluid sample, and correlating any detected binding to the physiological condition, the improvement comprising contacting the body fluid sample with an immunological binding partner which binds to both ##STR6## is hydroxylysyl pyridinoline or lysyl pyridinoline, J is pyroglutamic acid or glutamine, and (Leu) are optional leucine residues, and correlating any detected binding to degradation of type I collagen in vivo.