GFR Estimation

The level of GFR and its magnitude of change over time are vital to the detection of kidney disease, understanding its severity and for making decisions about diagnosis, prognosis, and treatment, including drug dosing. GFR cannot be measured directly in humans; instead GFR is assessed either as measured GFR (mGFR) or estimated GFR (eGFR).

GFR is measured using plasma or urinary clearance of exogenous filtration markers. It is a cumbersome procedure and can only be performed in specialized centers in specific circumstances. GFR is therefore usually estimated from endogenous filtration markers.

Estimating equations use endogenous filtration markers and other variables as surrogates for non-GFR determinants of the filtration markers to determine eGFR. There are one or more estimating equations for each filtration marker or a combination of filtration markers. The KDIGO (Kidney Disease: Improving Global Outcomes) only recommends the use of validated equations.

• Creatinine-based equations
• Cystatin C-based equations
• Approach to GFR evaluation
• Implementation of 2021 CKD-EPI equations
• GFR calculators - NFK link
• NKF frequently asked questions about GFR estimates
• Downloadable script for calculating eGFR using SAS or R statistical software – Check the Calculators tab
• Panel eGFR equations