Blood sample (5 mL each) was obtained from each patient for analysis of blood biochemical indicators. The detected indicators included alanine aminotransferase (ALT), γ-glutamyl aminotransferase, adenosine deaminase (ADA), Aspartate aminotransferase, total cholesterol (TC), triglyceride, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), homocysteine (Hcy), blood glucose, urea nitrogen (BUN), creatinine (Cre), uric acid (UA), β2-microglobulin, cystatin C (Cys-C), and retinol binding protein (RBP). The detection was performed on an AU2700 full-automatic biochemical analyzer (Japan). The reference range for each indicator was as follows: ALT 9 to 50 U/L, γ-glutamyl aminotransferase 10 to 60 U/L, ADA 4 to 24 U/L, aspartate aminotransferase 15 to 40 U/L, TC 2.83 to 5.17 mmol/L, triglyceride 0.56 to 1.7 mmol/L, HDL-C 0.9 to 2.19 mmol/L, LDL-C 0 to 3.36 mmol/L, Hcy 6 to 17 μmol/L, glucose 3.9 to 6.1 mmol/L, BUN 3.6 to 9.5 mmol/L, Cre 57-111 μmol/L, UA 208 to 428 μmol/L, β2-microglobulin 0.8 to 1.8 mg/L, Cys-C 0.63 to 1.25 mg/L, and RBP 25 to 70 mg/L.