Abstract: Improved ELISA assay formats are described that provide for effective measurement of desmosine, an elastin degradation product, in urine samples. The urine samples can be effectively introduced into the assay with little or no sample preparation. The competitive ELISA assay based on high titer polyclonal antibodies is suitable for commercial application. Desirable antibodies can be generated using desmosine bound to a protein or the like using a protein crosslinking agent. The desmosine assay are found to be useful for the diagnosis of aortic aneurysms in which desmosine levels of patients with aortic aneurysms have been found to be significantly elevated relative to a control group.