Renal functional reserve

Abstract

Serum creatinine and glomerular filtration rate (GFR) are the current standard tests tomeasure kidney function. The baseline GFR does not reflect full function of the kidney sincehuman kidneys do not always work at full capacity. Similarly, serum creatinine is not a sensitivemeasure for kidney function or injury. In healthy individuals the GFR physiologically increasesin response to certain stresses or stimuli, such as protein loading.Renal functional reserve (RFR) is defined as the difference between the maximalglomerular filtration rate (generally determined after oral or intravenous protein loading) and thebaseline glomerular filtration rate. The absence of a normal RFR can help identify patients whoare more susceptible to kidney injury. The RFR is also important in patients who develop acutekidney injury and chronic kidney disease. Even though the GFR might return to a baselinelevel, there may be some loss of RFR which can make the patient more susceptible to anotherepisode of kidney injury.Acute kidney injury and chronic kidney disease are considered interconnected syndromes;each is a risk factor for the other. There are no current recommendations regarding theperformance of routine determinations of RFR. Physicians should focus on clinical history andphysical examination in patients with a history of prior episodes of acute kidney injury, monitorrenal function, and avoid nephrotoxic insults.