Disclosed are methods and compositions that are useful in the detection and therapy of diseases (e.g., emphysema) and damage that afflict the lungs. In some aspects, the compositions comprise a formulation enriched for a species of phosphatidylcholine, such as palmitoylmyristoyl phosphatidylcholine (16:0 / 14:0PC). The compositions may further be described as lung surfactant supplement preparations particularly useful in the treatment of pulmonary diseases and afflictions prevalent among premature infants, and in particular, Respiratory Distress Syndrome (RDS). A PC marker is also disclosed, 16:0 / 14:0PC, that may be used to detect pulmonary disease or reduced / compromised alveolar function in an animal. Phospholipid profiles of 16:0 / 14:0PC, 16:0 / 16:1PC and 16:0 / 16:0PC are also provided, and are correlated with particular pulmonary diseased states.