Use of Cystatin C to Assess Kidney Function
The laboratory plays a key role in the diagnosis and staging of chronic kidney disease. In order to detect kidney damage independent of GFR, tests include a urinalysis and quantification of protein in the urine. Abnormalities that would indicate CKD include proteinuria, albuminuria, and formed elements such as red cell casts. Sometimes patients have more subtle abnormalities that might be detected on a blood electrolyte panel or more sophisticated testing. Examples include an inability to acidify the urine, called renal tubular acidosis, or an inability to concentrate the urine, called nephrogenic diabetes insipidus. Finally, radiology studies might detect evidence of kidney scarring, also diagnostic of CKD by
As mentioned above, criterion 2 is entirely based on your GFR number. There are 2 methods to establish what a person’s GFR is. We can directly measure GFR. Strategies here would include 24-hour urine for creatinine clearance, or specialized testing such as an inulin clearance or iothalamate clearance techniques. Although these methods are useful in many settings, they are more involved and costly, and not particularly suitable for mass screening or frequent monitoring of patients. Fortunately, methods have been developed to estimate GFR based upon simple blood tests.
What Can We Measure?
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