CST4 and kidney injury: Blood samples were obtained during their visit, and the patients were categorized into two groups based on their cystatin-based estimated GFR (eGFRcys) values: a kidney injury group (eGFRcys < 60 mL/min/1.73 m2) and a non-kidney injury group (eGFRcys ≥ 60 mL/min/1.73 m2).