From the Guidelines
Cystatin C is a crucial biomarker for detecting early kidney disease and should be used in conjunction with creatinine to confirm eGFR in adults at risk for or with chronic kidney disease, as recommended by the 2023 guidelines in Diabetes Care 1. The clinical significance of cystatin, particularly cystatin C, lies in its role as a biomarker for kidney function, allowing for the early detection of kidney disease. According to the 2023 guidelines in Diabetes Care, combining filtration markers such as creatinine and cystatin C provides more accurate results and supports better clinical decisions than using either marker alone 1. Key points to consider include:
- Cystatin C is recommended for confirmatory testing in specific circumstances when eGFR based on serum creatinine is less accurate, such as in individuals with low muscle mass.
- Cystatin C may detect kidney dysfunction at an earlier stage than creatinine in people with diabetes.
- The use of cystatin C, especially in combination with creatinine, can lead to more accurate assessments of kidney function and, consequently, better management of chronic kidney disease.
In the context of human health, the significance of cystatin extends beyond its role in kidney disease. However, the most recent and highest-quality evidence, as presented in the 2023 Diabetes Care guidelines, emphasizes its importance in kidney function assessment 1. Therefore, the use of cystatin C as a biomarker for kidney disease detection and management is strongly supported by current evidence. This approach prioritizes morbidity, mortality, and quality of life outcomes by enabling earlier and more accurate diagnosis and treatment of kidney disease.
From the Research
Clinical Significance of Cystatin C
- Cystatin C is a nonglycosylated basic protein produced at a constant rate by all investigated nucleated cells, and its serum concentration is independent of age, sex, and muscle mass 2.
- It has been proposed as an improved marker of glomerular filtration rate (GFR) compared with serum creatinine level, especially in the early stages of chronic kidney disease 2, 3.
- Serum cystatin C concentrations have been found to relate to renal impairment and suggest that cystatin C is more sensitive to detect mild decreases in GFR 4.
Advantages of Cystatin C as a Marker of Kidney Function
- Cystatin C is superior to creatinine as a marker of kidney function, especially in the early stages of chronic kidney disease 3.
- It can be used in the creatinine "blind" area, in pediatric and the elderly population 3.
- Cystatin C could be used as a marker for cardiovascular risk assessment, in predicting and detecting preeclampsia, in patients with malignant diseases, etc. 3.
Limitations and Clinical Considerations
- The level of cystatin C should be interpreted carefully because there are factors that can affect its level regardless of the renal function (thyroid dysfunction, glucocorticoids use, malignancies etc.) 3.
- The 2012 Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommended using cystatin C to confirm the diagnosis of chronic kidney disease (CKD) determined by creatinine-based estimated glomerular filtration rate (eGFR) and to estimate kidney function when accurate eGFR estimates are needed for clinical decision-making 5.
- Fully automated assays using particle-enhanced turbidimetry or particle-enhanced nephelometry are available and the assays are precise, rapid and usable in clinical routine practice 6.