Traditions and innovations in assessment of glomerular filtration rate using creatinine to cystatin C

Abstract

Purpose of review Glomerular filtration rate (GFR) is the best index for kidney function and estimated GFR (eGFR) calculated from endogenous filtration markers like serum creatinine and cystatin C is widely used in clinical practice for chronic kidney disease diagnosis and prognostication. We sought to review the evolution of GFR estimating equations, nuances of eGFR interpretation, and utility of eGFR in drug dosing. Recent findings The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) serum creatinine eGFR equation was recently updated to exclude the race variable and the CKD-EPI creatinine–cystatin C equation demonstrated the highest reliability. Although calculated creatinine clearance by Cockcroft Gault has been traditionally used for drug dosing, the use of eGFR is slowly being adapted by the Food and Drug Administration for pharmacokinetic studies. However, the individual-level accuracy of eGFR using the CKD-EPI 2021 equations remained low, with the distribution of measured GFR at a given eGFR value spanning several CKD stages. Summary Although current methods of estimating GFR have improved in population measures of reliability, all have significant individual-level inaccuracies that can be an issue when clinical decision-making is contingent on the actual level of GFR. Modern methods of GFR measurements should be made widely available to enhance individualized patient decision-making.

Association of serum creatinine to cystatin C to waist circumference ratios and hypertension: evidence from China health and retirement longitudinal study

“…Firstly, Creatinine and cystatin C independently serve as markers of renal health ( 33 ). CCR, leveraging both markers, yields a more stable and reliable glomerular filtration rate (GFR) metric, enhancing the accuracy of renal function assessment ( 34 ). An elevated level of CCR may suggest an increase in the GFR ( 35 – 37 ), which plays a pivotal role in maintaining fluid balance and regulating blood pressure ( 38 ).…”

External Validation of a Novel Multimarker GFR Estimating Equation

“…However, the accuracy of creatinine-based estimating equations is limited by non-GFR determinants of creatinine such as muscle mass and nutritional intake. 1 , 2 While the addition of cystatin C to creatinine in GFR estimation had improved accuracy, 3 , 4 external validation of this equation still yielded certain population-level biases and individual-level inaccuracies. 4 , 5 In particular, the new race-free CKD Epidemiology Collaboration (CKD-EPI) equation substantially underestimates GFR among Black individuals between 40 and 65 years.…”