CRP and chronic obstructive pulmonary disease: The impact of particular blood biomarkers (e.g., C-reactive protein (CRP), high-sensitivity (hs)-CRP, interleukin (IL)-6, IL-8, tumor necrosis factor-α, lactate dehydrogenase (LDH), ferritin, D-dimer, neutrophil to lymphocyte ratio (NLR)) on the severity and prognosis of COPD has been widely investigated and described in studies and literature reviews [4,5,6,7,8,9,10].