The glomerular filtration rate is the evaluation of overall kidney function. Nuclear scintigraphy allows the measurement of individual kidney function. The individual kidney function may be very important in patients with a mass in one of the kidneys where surgical removal is being considered. The individual kidney function is important as a way to determine the impact of removing one of the kidneys. Another scenario where individual kidney function can be considered is in patients that have a subcutaneous ureteral bypass (SUB) placed. This may provide an insight into the individual kidney function in case the SUB becomes obstructed in the future.