A kidney function test provides the patient with two sets of numbers, explains the National Kidney Disease Education Program. One set of numbers come from the glomerular filtration rate GFR test that determines how well the kidneys filter blood. The other comes from the amount of albumin in the urine.
Kidneys are a filtration system for the body, cleaning impurities out of the blood, according to the NKDEP. If the GFR test returns numbers of 60 or higher, the numbers indicate a healthy and properly functioning set of kidneys. When the numbers are lower than 60 but higher than 15, the test indicates the possibility of kidney disease. If the test returns numbers lower than 15, there is a likelihood of kidney failure.
Albumin is a protein found in a patient's blood, which the kidneys filter out before releasing the urine, states the NKDEP. The less this protein appears in urine, the healthier the kidneys are. If the test for albumin in the urine returns a number below 30, the kidneys function normally. When the test returns numbers over 30, there is an indication of kidney disease. In some cases, a damaged kidney allows a small amount of albumin into the urine.