[Assessment of serum markers KL-6 and SP-D for interstitial pneumonia associated with connective tissue diseases].

There are a lot of difficulties in the estimation of interstitial pneumonia and subsequent pulmonary fibrosis associated with connective tissue diseases. Recently, serum KL-6 (KL-6) and serum surfactant protein D (SP-D) have been reported to be useful to estimate the severity of interstitial pneumonia. We investigated the usefulness of these serum markers comparing to the spirometric parameters in patients with interstitial pneumonia associated with connective tissue diseases. We found significant inverse correlation between KL-6 and spirometric % VC. Furthermore, KL-6 was more significantly inverse-related with %DLco. On the other hand, we found neither correlation between SP-D and %VC, nor between SP-D and %DLco, suggesting SP-D level seems to be not affected by the degree of pulmonary fibrosis itself. These results indicate that KL-6 is useful to estimate the severity of pulmonary fibrosis more precisely than SP-D in patients with interstitial pneumonia associated with connective tissue diseases.