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 measuring eGFR with cystatin C if creatinine-based eGFR is inconclusive or if there is a need for a more accurate assessment of renal function in specific clinical situations.