Clinical significance of serum Krebs von den Lungen-6 levels as reliable effective marker in COVID-19 patients
Background: Coronavirus Disease 2019 (COVID-19) is a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) related illness that has spread globally and may worsen as pulmonary fibrosis develops. Krebs von den Lungen-6 (KL-6) has been recommended as a marker of COVID-19 and the severity of the illness. It is a chemical that is mostly expressed by injured alveolar type II cells. In order to confirm KL-6 potential as a predictive biomarker of severity in patients with COVID-19, this pilot investigation measured blood concentrations of KL-6. Materials and Methods: One hundred and forty patients with COVID-19 participated in the research. According to the severity of the disease, the COVID-19 patients were classified into three groups: critical disease (n=43), severe disease (n=52), and mild/moderate disease (n=45), with (n=60) healthy volunteers as the control group. Blood samples were taken as well as all of the patients' fundamental clinical and demographic information. Results: The blood KL-6 concentration on admission was considerably greater in each group as compared to that in all COVID-19 cases (critical, severe, and moderate) and normal control participants (p<0.0001), which was positively correlated with age, SBP,DBP,WBCs, neutrophil, CRP, D-dimer, ferritin, FBG, ALT, AST, and ALP whereas, negative correlate with lymphocytes, SpO2, albumin, and vitamin D. A cutoff value of 207.5 U/ml for KL-6 predicted severe COVID-19 with a sensitivity of 93.6% and a specificity of 88.3% (AUC: 0.965, 95%CI 0.943–0.988; p<0.0001). Conclusion: Critical and severe COVID-19 patients had considerably higher serum KL-6 concentrations, which might be a valuable indicator of the disease's severity. High blood KL-6 concentrations in the early stage of COVID-19 should as soon be closely monitored in order to avoid the development of pulmonary fibrosis as possible.