[Diagnostic usefulness of cystatin C measurement]

Cystatin C is a new endogenous marker of renal function whose serum concentration correlates better with glomerular filtration rate than creatinine. Cystatin C has been suggested to be a marker of renal function). Cystatin C is a cysteine proteinase inhibitor. It is produced at a constant rate in all investigated nucleated cells, its gene is a housekeeping type. Cystatin C is freely filtered in the renal glomeruli and reabsorbed and catabolised in the proximal tubules. Reference intervals have been determined for cystatin C in adults and in children older than one year without gender differences. Several studies including adults and children with different renal diseases with various kidney function have suggested serum cystatin C to be a better marker of GFR than serum creatinine. Fully automated assays using particle-enhanced turbidimetry (PETIA) or particle-enhanced nephelometry (PENIA) are available and the assays are precise, rapid and usable in clinical routine practice.