Glomerular filtration rate of 60 or higher is in the normal range and indicates how well the kidneys filter blood, according to the National Kidney Disease Education Program. The rate is calculated using blood creatinine levels and the individual's size, age, sex and race.
This estimation of glomerular filtration may not be accurate for all individuals, such as the very young, very old, amputees or obese people, says WebMD. The main function of the kidneys is to filter waste and excess water from the blood to produce urine. Glomerular filtration rate along with urine albumin are the two tests used in determining the presence of kidney disease.