To study the performance of two contemporary sets of estimating equations for glomerular filtration rate, published by CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) and EKFC (European Kidney Function Consortium) that include one (creatinine or cystatin C only) and combined (creatinine and cystatin C) biomarkers, to assess their accuracy in a population with moderate chronic kidney disease. The gene discussed is CST3; the disease is chronic kidney disease.