Konstantinos Makris, Nikolaos Kafkas, in
Advances in Clinical Chemistry, 2012Neutrophil Gelatinase-Associated Lipocalin in Acute Kidney Injury
5.1 Urine Output
Urine output is a commonly measured parameter of kidney function in AKI. Following of urine output can be advantageous because it is a dynamic gage of kidney function and is measured continuously. Urine output can be a more sensitive barometer for changes in renal hemodynamics than biochemical markers of solute clearance. Dynamic changes to urine output have been integrated into the Risk, Injury, Failure, Loss and End-stage renal disease [RIFLE] classification of AKI [15]. However, the urine output is also of limited sensitivity and specificity, with patients capable of developing severe AKI, as detected by a markedly elevated serum creatinine, while maintaining normal urine output [i.e., nonoliguric AKI]. Because nonoliguric AKI has been described as having a better outcome than oliguric AKI, urine output is frequently used to differentiate AKI; however, the value of this distinction is questionable and can be frequently negated by the use of diuretics [16]. Oliguria has classically been defined as urine output of approximately