What is Cystatin C?
Cystatin C (CysC) is a crucial low molecular weight protein that is produced by all nucleated cells and is found in all biological fluids including plasma (serum), saliva, and urine. The Cystatin C is taken up by the proximal tubes and then metabolized so that it does not return into the bloodstream. As a result, serum Cystatin C closely correlates to glomerular filtration rate (GFR). The normal range of serum Cystatin C is around 0.62-1.15 mg/L (1). An abnormally high level of Cystatin C in your blood may point to renal dysfunction. In addition to renal dysfunction/disease, higher levels of Cystatin C can also point to diabetes, chronic inflammation, obesity, cancer, and hyperthyroidism (5,6).
A marker for GFR
Glomerular filtration rate (GFR) remains the ideal marker for kidney function & it is commonly assessed by measuring serum markers such as blood urea nitrogen & serum creatinine (4).
Our Cystatin C ELISAs (human, mouse, rat) can provide an avenue for assessing renal dysfunction especially following surgery. Together with Cystatin C, a GFR marker, urinary Cystatin C would be a biomarker of AKI and/or assessing response to therapeutic interventions in experimental and clinical research.
1. Murty, M S N et al. “Serum cystatin C as a marker of renal function in detection of early acute kidney injury.” Indian journal of nephrology vol. 23,3 (2013): 180-3. doi:10.4103/0971-4065.111840
2. National Institute of Diabetes and Digestive and Kidney Diseases. Explaining Your Kidney Test Results: A Tool For Clinical Use. 2014, August.
3. Kar S, Paglialunga S, Islam R. Cystatin C Is a More Reliable Biomarker for Determining eGFR to Support Drug Development Studies. J Clin Pharmacol. 2018 Oct;58(10):1239-1247. doi: 10.1002/jcph.1132. Epub 2018 May 18. PMID: 29775220.
4. Omar F Laterza, Christopher P Price, Mitchell G Scott, Cystatin C: An Improved Estimator of Glomerular Filtration Rate?, Clinical Chemistry, Volume 48, Issue 5, 1 May 2002, Pages 699–707,
5. Muslimovic, Alma et al. “Serum cystatin C – marker of inflammation and cardiovascular morbidity in chronic kidney disease stages 1-4.” Materia socio-medica vol. 27,2 (2015): 75-8. doi:10.5455/msm.2015.27.75-78
6. Muntner, Paul et al. “Overweight, obesity, and elevated serum cystatin C levels in adults in the United States.” The American journal of medicine 121,4 (2008): 341-8. doi:10.1016/j.amjmed.2008.01.003
7. Grubb, Anders. “Cystatin C is Indispensable for Evaluation of Kidney Disease.” EJIFCC vol. 28,4 268-276. 19 Dec. 2017