In Whitley’s case, the problem was how the severity of kidney disease is assessed. The usual protocol is to calculate a patient’s “estimated glomerular filtration rate” (eGFR), which measures the amount of a certain waste product in their blood and therefore shows how efficient their kidneys are at filtering it out. If the eGFR is below a certain level, it’s an indication that their kidneys are failing and they are eligible for a transplant.