Estimating glomerular filtration rate: is it good enough? And is it time to move on?

PURPOSE OF REVIEW

The aim is to examine a dominant narrative in nephrology over the past decade: that measured glomerular filtration rate (GFR) is the gold standard measure of kidney function; accurate assessment of GFR is critical and paramount; and further efforts to refine GFR estimation should continue.

RECENT FINDINGS

Studies that have simultaneously compared measured GFR and estimated GFR (using endogenous filtration markers such as creatinine, or newer ones such as cystatin C or β-trace protein) against some external metric of kidney function have failed to show that measured GFR is consistently superior, which is what one would expect if measured GFR were truly the 'gold standard.'

SUMMARY

Compared with estimated GFR, measured GFR does not consistently predict renal-related outcomes better. Clinical decision-making almost never requires precise and accurate knowledge of a patient's static GFR value. Efforts at perfecting cross-sectional estimates of GFR may have reached a point of diminishing returns.