Cystatin C
(CysC)
Sample type
Serum or plasma
Red-top tube, gel-barrier tube, or green-top (heparin) tube
Uses
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).A reduction in GFR causes a rise in the concentration of cystatin C.
Precautions
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%.
Interfering factors
Specimen other than serum or heparinized plasma; grossly hemolyzed (>1,000 mg/dL Hgb) samples; excessive turbidity and clots in samples
Pre_analytical errors
. Forget frozen sample
The corrective action
Frozen sample
Post-analytical errors
Write another patient’s name in the report
The corrective action
Make sure you write the correct name in the report
Reference Range
| Age | |
|---|---|
| 0 to 1 y | |
| Range (mg/L) | Not established |
| 2 to 50 y | |
| Range (mg/L) | 0.60−1.00 |
| 51 to 60 y | |
| Range (mg/L) | 0.67−1.14 |
| 61 to 70 y | |
| Range (mg/L) | 0.72−1.16 |
| 71 to 80 y | |
| Range (mg/L) | 0.78–1.15 |
| > 80 y | |
| Range (mg/L) | 0.87–1.12 |