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Cystatin C

Test Codes

EPIC: LAB8551, CYSC

Department

Chemistry

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: One Mint Green PST or one Red-top Serum tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. If a Red-top Serum tube is collected, transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: Centrifuged SST tube or 1.0 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Rejection Criteria

Grossly hemolyzed specimens.

Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Deliver to the appropriate testing station.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Automated Chemistry Laboratory

Performed

Sunday – Saturday, 24 hours a day.
Results available in 4 hours.

Reference Range

19 years – Adult:  0.51-1.05 mg/dL
0 – 18 years:  No reference range.

Test Methodology

Immunoturbidimetric.

Clinical Utility

Cystatin C is a low molecular weight cystein proteinase inhibitor that is produced by all nucleated cells and found in body fluids, including serum. Since it is formed at a constant rate and freely filtered by the kidneys, its serum concentration is inversely correlated with the glomerular filtration rate (GFR); that is, high values indicate low GFRs while lower values indicate higher GFRs similar to creatinine.

Cystatin C can be useful in monitoring GFR in patients where serum creatinine may be misleading such as very obese, elderly and malnourished patients.

CPT Codes

82610

Contacts

Last Updated

4/5/2022