ALB and chronic obstructive pulmonary disease: SP-A mass concentrations correlated strongly with particle number and particle mass concentrations in the whole group, i.e. in both COPD patients and healthy subjects (rs = 0.97 and 0.97, respectively; p<0.0001), and this was also the case regarding albumin (rs = 0.94 and 0.95, respectively; p<0.0001).