Use of Cystatin C to Assess Kidney Function
Therefore, efforts have been devoted to make serum creatinine a better estimate of GFR. The main factor that varies between individuals and influences serum creatinine independent of GFR is muscle mass, which in turn is the key determinant of creatinine production. Therefore, equations have been developed that estimate what a person’s creatinine production should be. The oldest example of such an equation is the Cockroft-Gault equation. This equation estimates creatinine clearance based upon serum creatinine together with age, gender, and weight. The MDRD estimated GFR, or eGFR, was developed using data from the Modification of Diet in Renal Disease study. This study only included patients with chronic kidney disease, who were placed on various diets in order to determine if a low-protein diet helped preserve kidney function. As part of the study, patient’s had their GFR measured using iothalamate clearance. The investigators then used data in their study to develop an equation that best estimated GFR. One problem with the MDRD equation is that it was developed using only persons with CKD, and therefore does not perform very well in normal individuals. Therefore, a newer equation has been developed using a mixed population of patients with and without CKD. This equation is called the CKD-EPI equation. So far it is used mostly for research, but may make it into clinical practice sometime in the future.
Can We Turn the Serum Into a Better Estimate?
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