Aids in the assessment of glomerular filtration rate in patients for whom serum creatinine may be misleading, such as the very obese, elderly, or malnourished patients.
Specimen Sources
Blood, ArterialBlood, CapillaryBlood, Central LineBlood, Venous
Specimen Types
Blood
Container
MT Grn
Collection Instructions
Container/Tube: Gold top or Mint Green Li Heparin tube Specimen: 1 mL serum or plasma (0.5 mL min) Transport Temperature: Refrigerated Stability: 7 Days Refrigerated
Specimen Volume
1 mL serum or plasma (0.5 mL min)
Transport Instructions
Refrigerated
Specimen Stability
7 Days Room Temperature 7 Days Refrigerated 24 months Frozen
Methodology
Immunoturbidimetric
Days Performed
Sunday - Saturday 24 hours a day
TAT same day
Performing Laboratory
Northwell Health Laboratories
CPT
82610
LOINC Code: 87430-5
PDM
1559167
Only Orderable at Locations:
Orderable Everywhere
Results
Component Name
Base Name
Common Name
External Name
CYSTATIN C, S
CYSTATIN
CYSTATIN C, S
Cystatin C, S
EGFR BY CYSTATIN C
EGFRC
EGFR BY CYSTATIN C
eGFR by Cystatin C
Result Interpretation
CYSTATIN C Males: 0 days-22 years: no reference values established 23-29 years: 0.60-1.03 mg/L 30-39 years: 0.64-1.12 mg/L 40-49 years: 0.68-1.22 mg/L 50-59 years: 0.72-1.32 mg/L 60-69 years: 0.77-1.42 mg/L 70-79 years: 0.82-1.52 mg/L >79 years: no reference values established Females: 0 days-22 years: no reference values established 23-29 years: 0.57-0.90 mg/L 30-39 years: 0.59-0.98 mg/L 40-49 years: 0.62-1.07 mg/L 50-59 years: 0.64-1.17 mg/L 60-69 years: 0.66-1.26 mg/L 70-80 years: 0.68-1.36 mg/L 81-86 years: 0.70-1.45 mg/L >86 years: no reference values established
eGFR >60 mL/min/BSA eGFR will not be calculated for patients under 18 years.
Interpretation: Cystatin C: Cystatin C inversely correlates with the glomerular filtration rate (GFR), that is elevated levels of cystatin C indicate decreased GFR. Cystatin C may provide more accurate assessment of GFR for very obese, elderly, or malnourished patients than creatinine. Cystatin C equation does not require patient ethnic data, and can be used for those patients with this information unavailable.
Due to immaturity of renal function, cystatin C levels are higher in neonates <3 months of age.(2)
Estimated Glomerular Filtration Rate (eGFR): Chronic kidney disease (CKD) is defined as the presence of: persistent and usually progressive reduction in GFR (GFR <60 mL/min/1.73 m[2]) and/or albuminuria (>30 mg of urinary albumin per gram of urinary creatinine), regardless of GFR.
According to the National Kidney Foundation Kidney Disease Outcome Quality Initiative (K/DOQI) classification, among patients with CKD, irrespective of diagnosis, the stage of disease should be assigned based on the level of kidney function:
