Abstract: The invention pertains to the use of a specific biomarker of elastin degradation (desmosine) that measures the extent and progression of chronic obstructive pulmonary disease (COPD). In addition to potentially serving as a screening procedure for COPD, it provides a real-time measure of COPD drug efficacy and may therefore supersede the use of less sensitive tests such as pulmonary function studies and computed tomography. Equally important, the current invention constitutes a marked improvement for measuring desmosine in tissues and body fluids by greatly shortening the time for detection of this molecule in liquid chromatography-tandem mass spectrometry (LC-MS-MS) assays that are the gold standard for such measurements. Unlike previous methods, the invention allows for the use of LC-MS-MS without modification, so the method can be applied to any laboratory that uses this equipment for other measurements.