Use of Cystatin C to Assess Kidney Function
Several large studies have recently suggested a particularly useful niche for cystatin C testing. In the next 2 slides I will show some data from 2 of these studies. The REGARDS study included over 26,000 adults monitored over 7 years for risk of stroke. Data were also analyzed for other outcomes including risk of CKD. As shown in the table on the left, an elevated serum creatinine alone at baseline did identify persons at risk for subsequent CKD. Cystatin C alone was slightly better, while an elevated albumin creatinine ratio in the urine, or ACR, was better than either creatinine or cystatin C alone. Persons with an increased cystatin C and urinary albumin creatinine ratio at baseline had much higher rates of subsequent CKD. This combination performed better than creatinine and urine albumin creatinine ratio for predicting risks. Persons with an elevated creatinine and cystatin C also had much higher rates of CKD than either marker alone. Finally, combining all three markers clearly identified patients at very high risk for subsequent CKD.
The table on the right shows that risk of mortality was also associated with cystatin C levels. Persons with a normal eGFR by MDRD using serum creatinine, but an increased cystatin C level, had a 2-fold increased risk of mortality over the 7 years of the study. This increased to 3-fold if urinary albumin creatinine ratio was also increased. Mortality was highest in persons and had an increased creatinine, cystatin C, and urine albumin creatinine ratio, 5.6-fold above those with kidney function that was normal by all criteria.
At Risk Of CKD Progression4
Jump to section:
- A Case
- What do the kidneys do?
- Why Measure Renal Function?
- How Is Chronic Kidney Disease (CKD) Defined?
- Stages of Chronic Kidney Disease
- Laboratory Assessment of Kidney Function: What Can We Measure?
- Creatinine as a Marker of GFR
- Creatinine as a Marker of GFR: It Works But...
- How Can We Turn the Serum Creatinine Into a Better Estimate of GFR?
- Revised eGFR Equation (ID-MS version)
- eGFR Equation Works, But it's Not Perfect
- What About Cystatin C?
- Mayo Renal Laboratory Cystatin C By Particle Enhanced Turbidometric Immunoassay (PETIA)
- Comparison To Current Nephelometric Assay (PENIA) Reveals 23% Bias
- Cystatin C PENIA Assay Shift (19%)
- Cystatin C eGFR Using Published Equation* Performs Well3
- Cystatin C Equations Categorize Patients Slightly Better Than MDRD eGFR
- Cystatin C Reference Range
- PETIA Cystatin C Reference Range
- Cystatin C: Useful To Confirm Those At Risk Of CKD Progression And Its Complications (REGARDS)4
- Cystatin C: CKD Progression and Complications (MESA and CHS)5
- Cystatin C in the Acute Hospitalized Setting6
- Back to Our Patient
- Potential Interventions