Cystatin C as a Predictor for Acute Kidney Injury

Abstract

Background: Acute kidney injury (AKI) is a frequent and serious clinical complication encountered in hospitalized patients, particularly in critically ill individuals and those undergoing major surgical or interventional procedures. It is associated with increased morbidity, mortality, prolonged hospital stay, and a higher risk of progression to chronic kidney disease. Despite its clinical significance, early diagnosis of AKI remains challenging, which limits the opportunity for timely preventive and therapeutic interventions. Serum creatinine, the conventional biomarker used for diagnosing AKI, has well-recognized limitations. Its concentration is affected by several non-renal factors, including age, sex, muscle mass, nutritional status, and fluid balance. Moreover, serum creatinine typically rises only after a substantial decline in glomerular filtration rate, resulting in delayed detection of renal injury. These limitations have driven the search for more sensitive and earlier biomarkers of kidney dysfunction. Importantly, serum cystatin C levels are less influenced by muscle mass and other demographic factors compared to serum creatinine. Emerging evidence suggests that cystatin C may rise earlier than serum creatinine in the setting of acute kidney injury, allowing for earlier identification of patients at risk. Therefore, evaluating the predictive value of cystatin C for AKI may improve early diagnosis, risk stratification, and clinical outcomes.

Conclusion: Cystatin C appears to be a reliable and sensitive biomarker for the early prediction of acute kidney injury. Its early rise compared to serum creatinine may allow for timely identification of patients at risk of AKI and facilitate earlier preventive and therapeutic interventions.