From the Guidelines
Cystatin C is a superior marker for kidney function due to its constant production rate, lack of secretion or reabsorption, and independence from muscle mass, age, gender, or diet, making it a more reliable indicator of glomerular filtration rate (GFR) compared to creatinine. This is supported by the most recent guidelines and recommendations, such as those from the 2023 Diabetes Care study 1, which suggest that cystatin C can detect kidney dysfunction at an earlier stage than creatinine in people with diabetes. The use of cystatin C is particularly valuable in specific populations where creatinine-based estimates may be inaccurate, such as:
- The elderly
- Children
- Patients with liver disease
- Those with reduced muscle mass Cystatin C rises earlier in kidney disease than creatinine, allowing for earlier detection of declining kidney function, and its use can provide more precise assessment of kidney function, especially in the critical GFR range of 45-59 ml/min where early intervention is most beneficial, as recommended by the 2022 American Journal of Kidney Diseases study 2. Additionally, combining filtration markers (creatinine and cystatin C) is more accurate and would support better clinical decisions than either marker alone, as stated in the 2023 Diabetes Care study 1. Overall, the use of cystatin C as a marker for kidney function can improve the accuracy of GFR estimates and support better clinical decisions, which can ultimately lead to better patient outcomes in terms of morbidity, mortality, and quality of life.
From the Research
Advantages of Cystatin C as a Marker for Kidney Function
- Cystatin C has been shown to be a reliable and accurate marker of kidney function across diverse populations 3
- It has fewer non-GFR determinants compared to serum creatinine, making it a more accurate estimate of glomerular filtration rate (GFR) 4
- Cystatin C is less affected by diet and muscle mass, which can impact serum creatinine levels 4
- It is more strongly associated with all-cause mortality and cardiovascular events, making it a valuable tool for risk stratification 4
Clinical Considerations for Using Cystatin C
- The 2012 Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommend using cystatin C to confirm the diagnosis of chronic kidney disease (CKD) and to estimate kidney function when accurate eGFR estimates are needed 3
- The National Kidney Foundation (NKF) and American Society of Nephrology (ASN) Joint Task Force recommend increasing the availability and clinical adoption of cystatin C to assess kidney function 3
- Cystatin C may be particularly useful in patients for whom creatinine is an inadequate marker or for whom more cumbersome methods of GFR measurement are impractical 5
Comparison to Other Markers of Kidney Function
- Serum cystatin C has been shown to have a higher diagnostic accuracy than serum creatinine and calculated creatinine clearance from the Cockcroft-Gault formula in female patients with mildly to moderately impaired kidney function 6
- Cystatin C has been compared to other markers of GFR, including serum creatinine and calculated creatinine clearance from the modification of diet in renal disease (MDRD) formula, and has been found to be a reliable marker of GFR in patients with CKD stages 2-3 6