GPT and chronic obstructive pulmonary disease: Alb, albumin; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; BUN, blood urea nitrogen; CK, creatine kinase; CKD, chronic kidney disease; Creat, creatinine; CRP, C-reactive protein; COPD, chronic obstructive pulmonary disease; KL-6, Krebs von den Lungen-6; LDH, lactate dehydrogenase; Plt, platelet; T-bil, total bilirubin; WBC, white blood cell.