Cystatin C

Specimen:

5 mL blood in lithium heparin or plain tube.

Method:

Immunoassay.

Reference Interval:

1-18 years: 0.5-1.3 mg/L

Adults: 0.5-1.0 mg/L.

Application:

Assessment of glomerular filtration rate, see Creatinine clearance.

Interpretation:

Cystatin C can be used for the diagnosis of impaired renal function. The reciprocal of the serum cystatin C concentration has been shown in several studies to have a better correlation to GFR than serum creatinine. In addition, significant increase in serum creatinine is not detected until after the GFR has fallen by 50 percent.

Cystatin C provides a good means of evaluating renal function in paediatric patients because it declines from neonatal levels to near adult values by one year of age.

Reference:

Laterza OF et al. Clin Chem 2002; 48(5): 699-707.