Use of Cystatin C to Assess Kidney Function
At the Mayo Clinic our renal function lab can directly measure GFR using iothalamate clearance. This slide depicts measured GFR in 3 large groups of patients tested in our lab: Normal individuals being evaluated as potential kidney donors, persons that have already donated a kidney, and persons with known chronic kidney disease. The slide shows measured GFR, or iothalamate clearance, on the Y-axis, and the MDRD estimated GFR on the X-axis. Persons with chronic kidney disease are shown in the small black dots. The black line shows the correlation of measured GFR and estimated GFR, and falls directly over the line of identity. Therefore, the MDRD equation estimates GFR very well in patients with known chronic kidney disease. The normal potential kidney donors are shown in blue, and have measures GFR that is slightly higher than the estimated GFR. This data shows that the MDRD equation underestimates GFR in persons with normal kidney function. Finally, the red circles and line show data from persons post-kidney donation. Their values fall roughly halfway between the chronic kidney disease and normal populations.
eGFR Equation Works, But it's Not Perfect
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