[Serum type III procollagen peptide in patients with pneumoconiosis]

Early diagnosis of lung fibrosis has been hampered by the lack of a simple, convenient and specific method. Recently Rohde et al. developed an assay method for Type III procollagen peptide. Type III procollagen peptide, an extension peptide released during the biosynthesis of collagen Type III, has been known as a good marker for hepatic fibrosis. Therefore, we applied this assay to the patients with idiopathic pulmonary fibrosis, lung fibrosis in collagen disease and silicosis. And also we measured the serum level of the peptide in the healthy workers being exposed to silica. Normal value of the peptide in adults was 8.3 +/- 2.6 (mean +/- SD; n = 32) ng/ml. The upper value over mean + 2SD, 13.4 ng/ml, was regarded as abnormal value. Six patients with idiopathic pulmonary fibrosis, and lung fibrosis in collagen disease showed a significant increased level of 19.0 +/- 9.6 ng/ml (P less than 0.02). Four of 6 patients had abnormal high values. On the other hand, the patients with silicosis had not so high levels of peptide (12.6 +/- 6.5 ng/ml; n = 24; P less than 0.01), but 25% of the patients showed abnormal values. There were 2 cases among 19 healthy workers being exposed to silica who revealed slight abnormal values, 15.6 and 16.7 ng/ml. These observations suggest that the assay has a prognostic value for lung fibrosis and also is useful for the early detection of active lung fibrosis in the workers, even though Type III procollagen biosynthesis is already low in the late stages of silicosis.