Cystatin C blood measurements may be useful in assessing the risk of complications associated with chronic kidney disease (CKD).

Cystatin C is a stronger predictor of clinical outcomes associated with CKD than is creatinine, but its clinical role is unclear, according to researchers (J Am Soc Nephrol. 2011;22:147-155). Creatinine levels are often measured to evaluate kidney function, but are inaccurate in detecting mild kidney impairment. In addition, creatinine levels can vary with muscle mass and protein intake.

Data from 11,909 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) and the Cardiovascular Health Study (CHS) were used to define CKD using both creatinine and cystatin C. For the MESA enrollees, those with creatinine-defined CKD had a similar risk of premature death as persons without CKD. However, those with CKD based on cystatin C measurements had more than threefold increased risk, and those with CKD as identified by both creatinine and cystatin C measurements had nearly a twofold greater risk of premature death than persons without CKD.

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In the CHS cohort, those with creatinine-only CKD had a similar risk of premature death as those without CKD; those with CKD as per cystatin C levels had a 1.78-fold increased risk; and those with CKD based on both tests had a 1.74-fold increased risk.

“The creatinine-based CKD definition captures a large number of adults who are actually at low risk for important complications of CKD,” explained a statement announcing the group’s findings. “We believe that cystatin C should be a confirmatory test among persons identified as having impaired kidney function based on creatinine levels.”