Utilidad clínica de la reserva funcional renal

Renal function reserve (RFR) represents the capacity of the kidney to increase glomerular filtration rate (GFR) in response to certain physiological or pathological stimuli or conditions.

Baseline GFR displays variable values according to the diet or other factors, and may be normal even when there is an important lowering of nephron number. Once baseline GFR is determined, RFR can be assessed clinically by oral protein load or intravenous aminoacid infusion.

RFR is the difference between peak (stress-induced) GFR and basal GFR. In clinical scenarios where hyper-filtration is present (high baseline GFR due to pregnancy, hypertensive or diabetic nephropathy, solitary kidney or kidney donors) RFR may be fully or partially used to achieve normal or supra-normal renal function.

RFR test may represent a sensitive and early way to asses kidney functional decline and recovery. In cases of healing with a defect and fibrosis, clinical assessment may suggest a complete recovery, but a reduced RFR may be a sign of a maladaptive repair or sub-clinical loss of renal mass. Therefore, a reduction of RFR may represent the equivalent of renal frailty or susceptibility to insults. The main aim of this article is to review the concept of RFR, its utility in different clinical scenarios and future perspective for its use.