Cystatin C and acute changes in glomerular filtration rate

The identification of an effective marker of acutely changing kidney function is a priority in clinical nephrology. While serum creatinine is the most widely used surrogate for glomerular filtration rate (GFR), its vulnerability to non-glomerular clearance results in biased estimates of GFR and may delay the identification of acute changes. Alternatively, cystatin C (CysC) has been recognized as a promising marker of GFR. Controlled physiological studies in diabetes, protein-induced glomerular hyperfiltration and extreme exercise demonstrated that acute changes in CysC provide a better approximation of GFR than serum creatinine. Clinical studies examining contrast induced nephropathy, acute kidney injury, and kidney transplantation have also demonstrated several possible advantages of CysC with respect to accurately measuring GFR and early diagnosis of renal dysfunction. CysC measurements also provide ancillary benefits such as improved prediction of patient outcomes and prognosis. Our aim was to review the literature on short-term changes in CysC over days, weeks and months to explore the clinical utility of CysC in the acute setting. Based on existing evidence, CysC may improve clinicians' ability to detect acute changes in kidney function.