Cystatin C: a Promising Marker and Predictor of Impaired Renal Function

  1. Justin Westhuyzen
  1. Department of Medicine, Christchurch School of Medicine & Health Sciences, University of Otago, Christchurch, New Zealand
  1. Address correspondence to Justin Westhuyzen, Ph.D., Department of Medicine, Christchurch School of Medicine & Health Sciences, University of Otago, PO Box 4345, Christchurch, New Zealand; tel 64 3 364 0017; fax 64 3 364 0935; e-mail j.westhuyzen{at}chmeds.ac.nz.

Abstract

Cystatin C is a relatively stable protein in serum and heparinized plasma that shows promise as a convenient measure of glomerular filtration rate (GFR). However, it is becoming clear that the relationship between cystatin C and GFR can depend on the clinical presentation. Factors influencing cystatin C levels are those that affect the rate of synthesis of the protein, such as thyroid status and the use of steroids. As with all laboratory tests, results should be interpreted in the light of the method’s known limitations and in conjunction with other clinical and laboratory information. Nevertheless, accumulating evidence suggests that cystatin C is a useful biomarker for renal function, and may even be the method of choice in a range of clinical situations, from GFR surveillance in diabetics to the assessment of acute kidney injury in critically ill patients.

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