Glomerular filtration is the process by which the kidneys filter
the blood, removing excess wastes and fluids. Glomerular filtration rate (GFR)
is a calculation that determines how well the blood is filtered by the kidneys,
which is one way to measure remaining kidney function. GFR is also used to find the stage of chronic kidney disease.
Glomerular filtration rate is usually calculated using a
mathematical formula that compares a person's size, age, sex, and race to serum
creatinine levels. A GFR under 60 mL/min/1.73 m² may mean kidney
disease—the lower the GFR number, the worse the kidney function. This number is
an estimate. It may not be a good measure of kidney health in some people, such
as the very young or very old, amputees, or obese people.