The present invention relates to methods of diagnosing, monitoring, and treating elastin fiber injuries. In additional preferred embodiments, the present invention relates to methods of validating candidate compounds for use in treating chronic obstructive pulmonary disease (COPD), chronic bronchitis, emphysema, refractory asthma, and other related diseases. Examples of such methods include determining if the candidate compound decreases the degradation of elastic fiber in a patient administered the candidate compound by measuring, using mass spectrometry employing an internal standard, a marker of elastic fiber degradation in a sample of a body fluid or a tissue of the patient. The invention provides that a decrease in the presence of the marker compared to a control validates that the candidate compound is effective to treat, prevent, or ameliorate the disease.