Errors induced by indexing glomerular filtration rate for body surface area: reductio ad absurdum

In this article, we will discuss an important but underrecognized topic in nephrology. Indeed, indexing glomerular filtration rate (GFR) for body surface area (BSA) is often done by habit, because everyone does it and without raising any questions. Only a scant literature on this topic has been published in recent decades. Regarding guidelines on estimating and measuring GFR, only the Australian ones deeply discuss this topic. However, indexing GFR is not free from criticisms and may be misleading, especially in some specific populations. As we have pointed out, indexing GFR for BSA has very limited consequences on GFR results in a ‘normal’ body size population, but its consequences are substantial in other populations such as obese or anorectic patients [1,2]. In this editorial, we would like to show the limitations of such an indexation and give some evidence of its inadequacy.