Laboratory: Clinical Biochemistry  (SENDOUTS)
Test Name:
CYSTATIN C - (S) or (P)
Test Code: MIS8
Clinical Information:
Description: Cystatin C (CysC) may have advantages over creatinine eGFR in certain patient groups in whom serum creatinine may not be a reliable marker of renal function.

Cystatin C is a low molecular weight (13,250 kD) cysteine proteinase inhibitor that is produced by all nucleated cells and found in body fluids, including serum. It is formed at a constant rate and freely filtered by the kidneys, and 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.

 

Both creatinine and CysC are freely filtered by glomeruli; however CysC, is reabsorbed and metabolized by proximal renal tubules. Under normal conditions, significant CysC does not enter the urine.

 

See attached Cystatin C Testing Indications in Patients AUG-2024 for full indications. 

THIS TEST WILL ONLY BE MADE AVAILABLE TO NEPHROLOGISTS AND ENDOCRINOLOGISTS FOR THE INDICATIONS LISTED


Test Approval Requirements: Clinical Biochemist Approval Required F260-11-02 Biochemistry Approval for Test Referral Form

THIS TEST WILL ONLY BE MADE AVAILABLE TO NEPHROLOGISTS AND ENDOCRINOLOGISTS FOR THE INDICATIONS LISTED ABOVE.
Collection Devices:
Lithium Heparin plasma is also acceptable.
Specimen Required:
Serum: 1.0 mL
Pediatric Serum: 1.0 mL

Special Processing: Separate and freeze immediately. Store and ship frozen.

Specimen Stability: 

Refrigerated: 7 days

Frozen (-20°C or lower): Plasma (6 months), Serum (24 months)

Other comments: Specimen is unsuitable for analysis if received thawed by the referral lab.
Referral:

Shipping & Storage: Store and ship frozen.

Referred Out Location: Specimens are referred out from HSC-MS5 to In-Common Laboratories (ICL)

 

Test ID: CYSTC

Test Name: Cystatin C with Estimated Glomerular Filtration Rate (eGFR), Serum/Plasma

ICL Test Menu Entry: https://iclabs.ca/test/606/

 

Testing Location:

Children's Hospital Eastern Ontario (CHEO)

401 Smyth Road

Ottawa ON K1H 8L1
Requisition:
Reference Values:
Reference Intervals: 

Cystatin C:  ≤ 1.20 mg/L

CysC eGFR:  ≥ 90 mL/min/1.73m2


Method of Analysis: Immunoturbidimetric, on Roche Cobas c501 platform

 

Reference Value Document Links: https://iclabs.ca/test/606/
Availability:
Within 2 Weeks
See Also:
More Information:
Interpretation & Assay Interferences: Report includes Cystatin C concentration and calculated eGFR.

 

For patients <18 years of age, eGFR will be calculated using the Schwartz Cystatin C Equation (Kidney Int. 2012. 82(4): 445-53).

 

For patients ≥18 years of age, eGFR will be calculated using the 2012 CKD-EPI Cystatin C Equation (NEJM. 2012. 367(1): 20-29).