Knowing your GFR-when is the number not (exactly) the number?

Abstract

All methods used to measure and estimate glomerular filtration rate (GFR) are associated with systematic or random error, which leads to differences in measured GFR (mGFR) and estimated GFR (eGFR) from "true GFR." In this issue of Kidney International, Rowe et al. evaluate time-to-time variability using repeated assessments of mGFR and eGFR within a short time frame. They show that biological variability is larger for mGFR than eGFR, and the magnitude of reference change values when interpreting changes in mGFR and eGFR.