Krebs von den Lungen‐6, a promising marker in evaluating the severity of interstitial lung disease in Egyptian rheumatoid arthritis patients

Krebs von den Lungen-6 (KL-6) is one of the mucins associated with interstitial lung disease. We aimed to assess the value of KL-6 as a marker for detecting the presence of interstitial lung disease in Egyptian rheumatoid arthritis patients and to evaluate its ability to assess severity in different grades of interstitial lung disease. The study included 89 rheumatoid arthritis patients; 64 patients with interstitial lung disease and 25 patients without interstitial lung disease. Serum levels of KL-6 were assessed using enzyme linked immunosorbent assay. Levels of KL-6 were higher in patients with interstitial lung disease compared to patients without interstitial lung disease (P< 0.001). KL-6 levels were significantly higher in grade 4 patients than those in grades 1 and 2. Also, KL-6 levels were significantly higher in grade 3 patients than those in grades 1 and 2. Kl-6 levels were also higher in grade 2 patients compared to grade 1 patients. Finally, no difference was observed between grade 4 patients and grade 3 patients. KL-6 levels were significantly higher in usual interstitial pneumonia pattern compared other patterns (P=0.015). In conclusion, KL-6 is a potential circulating biomarker that may have a substantial role in detecting the presence and evaluating the severity of interstitial lung disease among rheumatoid arthritis patients.