Cystatin C with Estimated Glomerular Filtration Rate (eGFR), Serum
Use
This test is utilized for assessing kidney function in patients suspected of having kidney disease, particularly in cases where serum creatinine levels may be misleading, such as in very obese, older adults, or malnourished patients. It is also used to monitor treatment response in patients with kidney disease and provides an index of glomerular filtration rate (GFR). The eGFR is calculated using the CKD-EPI Cystatin C equation for adults and the Schwartz equation for children, offering an assessment less influenced by muscle mass variations and more accurate during rapidly changing kidney functions.
Special Instructions
Not provided.
Limitations
The estimated glomerular filtration rate (eGFR) derived from this test is not a precise measure of GFR and may be impacted by non-renal factors such as inflammation. The cystatin C-based eGFR may present some advantages over creatinine-based estimates, especially in patients with high or low muscle mass, as it is less affected by non-renal factors related to body composition.
FDA ApprovedNew York Approved
Methodology
Immunoassay (Immunoturbidimetric)
Biomarkers
Cystatin C
ProteinEstimated Glomerular Filtration Rate (eGFR)
Analyte
LOINC Codes
- 87430-5 - Cystatin C + GFR by Cystatin C Pnl SerPl
- 33863-2 - Cystatin C SerPl-mCnc
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.25 mL
Container
Plastic vial; preferred: Serum gel tube; acceptable: Red top tube
Collection Instructions
Serum gel tubes should be centrifuged within 2 hours of collection. Red-top tubes should also be centrifuged and serum aliquoted into a plastic vial within 2 hours.
Causes for Rejection
Gross hemolysis and gross icterus are causes for specimen rejection.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 30 days |