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HelpTest Code CYC Cystatin C
Useful For
Assessing kidney function for known or suspected kidney disease, but only when serum creatinine measurements are not reliable (such as obese, elderly, or malnourished patients).
Synonyms/Keywords
CyCSpecimen Requirements
| Fasting Required | Specimen Type | Preferred Container/Tube | Acceptable Container/Tube | Specimen Volume | Specimen Minimum Volume (allows for 1 repeat) |
Pediatric Minimum Volume (no repeat) |
|---|---|---|---|---|---|---|
| No | Serum | Red Top Tube (RTT) or Serum Separator Tube (SST) | 0.5 mL | 0.4 mL | 0.3 mL |
Collection/Processing Instructions
Separate serum from cells within 2 hours of collection.
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerate | 7 days |
| Frozen | 3 months |
Rejection Criteria
Plasma samples
Test Information
Cystatin C is a low molecular weight cysteine proteinase inhibitor that is produced throughout the body and is freely filtered by glomeruli. The serum concentration of cystatin C remains unchanged with infections, inflammatory or neoplastic states, and is not affected by body mass, diet, or drugs. The serum concentration is inversely correlated with the glomerular filtration rate. When using serum cystatin C to calculate GFR, the CKD-EPI cystatin equation is recommended (which is utilized by Marshfield Labs).
Interpretations
Cystatin C inversely correlates with the glomerular filtration rate (GFR). Elevated levels of cystatin C indicate decreased GFR. Cystatin C may provide more accurate assessment of GFR in patients with muscle wasting or chronic illness.
References
- Villa P, Jimenez M et al.: Serum cystatin C concentration as a marker of acute renal dysfunction in critically ill patients. Critical Care 2005'9:R139-143
- Inker LA et al.: Estimating glomerular filtration rate from serum creatinine and cystatin C. N Engl J Med 2012; 367:20-29
Reference Range Information
| Performing Location | Reference Range |
|---|---|
| Marshfield |
Cystatin C: Adults (over age 18 years): 0.56 - 0.99 mg/L eGFR will not be calculated for patients 18 years or under |
Marshfield Labs Performing Department
Marshfield Labs Immunodiagnostics
Performing Information
| Performing Location | Day(s) Test Performed | Analytical Time | Methodology/Instrumentation |
|---|---|---|---|
| Marshfield |
Monday- Friday |
6-8 hours Analytic time may be extended if single frozen specimen is sent for multiple tests |
Turbidimetric method/The Binding Site Optilite analyzer |
CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 82610 |
Outreach CPT Codes
| CPT | Modifier (if needed) |
Quantity | Description | Comments |
|---|---|---|---|---|
| 82610 |
Ordering Applications
| Ordering Application | Description |
|---|---|
| Cerner | Cystatin C |
| COM | Cystatin C |