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Expected Turnaround Time
3 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Related Documents
Specimen Requirements
Specimen
Serum or plasma
Volume
0.5 mL
Minimum Volume
0.2 mL
Container
Red-top tube, gel-barrier tube, or green-top (heparin) tube
Collection
Separate serum or plasma from red blood cells.
Storage Instructions
Room temperature
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Causes for Rejection
Specimen other than serum or heparinized plasma; grossly hemolyzed (>1,000 mg/dL Hgb) samples; excessive turbidity and clots in samples
Test Details
Use
Since it is formed at a constant rate and freely filtered by the healthy kidney, cystatin C is a good marker of renal function. Serum concentrations of cystatin C are almost totally dependent on glomerular filtration rate (GFR).1,2 A reduction in GFR causes a rise in the concentration of cystatin C.
Limitations
Cystatin C has not been shown to be affected by factors such as muscle mass and nutrition, factors which have been demonstrated to affect creatinine values. In addition, a rise in creatinine does not become evident until the GFR has fallen by approximately 50%.
Methodology
Turbidimetric (directly traceable to ERM-DA471/IFCC, the international standard reference material)
Reference Interval
See table.
Age | Range (mg/L) |
|---|---|
0 to 1 y | Not established |
2 to 50 y | 0.60−1.00 |
51 to 60 y | 0.67−1.14 |
61 to 70 y | 0.72−1.16 |
71 to 80 y | 0.78–1.15 |
>80 y | 0.87–1.12 |
Footnotes
1. Grubb A. Diagnostic value of analysis of cystatin C and protein HC in biological fluids. Clin Nephrol. 1992; 38(Suppl 1):S20-7. 1284235
2. Coll E, Botey A, Alvarez L, et al. Serum cystatin C as a new marker for noninvasive estimation of glomerular filtration rate and as a marker for early renal impairment. Am J Kidney Dis. 2000; 36:29-34.10873868
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 121251 | Cystatin C | 33863-2 | 121252 | Cystatin C | mg/L | 33863-2 |
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The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf