Correlation of Serum Krebs Von Den Lungen-6 Levels with Fibrosis Score on High Resolution Chest Tomography and Pulmonary Function Parameters in Treatment Naïve Idiopathic Pulmonary Fibrosis.

Background: While serum Krebs von den Lungen-6 (KL-6) has been found to be a helpful biomarker in interstitial lung diseases for evaluating disease severity and progression, especially in connective tissue disease-associated interstitial lung disease (CTD ILD) and idiopathic non-specific interstitial pneumonia (NSIP), data on correlation of serum KL-6 levels with radiological fibrosis and pulmonary function parameters is lacking in treatment na & iuml;ve Idiopathic Pulmonary Fibrosis (IPF) patients. Methods: Serum KL-6 levels were measured in thirty-nine treatment na & iuml;ve newly detected IPF patients using automated immunofluorescence enzyme assay (AIA) by Tosoh Corporation, bioscience division, Tokyo, Japan. Fibrosis score was calculated by independent visual assessment of the pattern and severity of abnormalities on high resolution computed tomography (HRCT) thorax. HRCT fibrosis scores were correlated with serum KL-6 levels and pulmonary function parameters like forced vital capacity (FVC), diffusion capacity of lung for carbon monoxide (DLco). Results: Median value of serum KL-6 levels was 1519 U/ml (range 199.41-6055 U/ml). There was positive correlation of serum KL-6 with HRCT fibrosis score (r=0.692, p<0.001) and negative correlation with FVC (r=-0.511, p=0.001) and DLco (r=-0.354, p=0.043). In the HRCT fibrosis score pattern subset analysis, the presence of reticulation revealed weak negative and statistically insignificant correlation (r=-0.116, p=0.481) while traction bronchiectasis and honeycombing exhibited statistically significant positive correlation (r=0.425, p=0.007; r=0.584, p<0.001 respectively) with serum KL-6 levels. Conclusion: Serum KL-6 levels showed a positive correlation with the degree of fibrotic abnormalities on HRCT thorax and pulmonary function parameters, indicating a potential use of serum KL-6 in monitoring of parenchymal fibrosis in Idiopathic Pulmonary fibrosis.