CYSTATIN C

Cystatin C is used to diagnose renal impairment in early stages. It is a better indicator of renal function than creatinine in the early stages of GFR impairment.
For confirmation of CKD, KDIGO 2012 Guideline recommends to measure eGFR with cystatin C if eGFR estimated by creatinine is between 45–59 ml/min/1.73 m2 (G3a) and no marker of kidney damage is present.