What Is the GFR on a Blood Test?

The GFR, or glomerular filtration rate, indicates how well the kidneys are filtering waste from the blood, states MedlinePlus. GFR is calculated using a formula that includes age, creatinine level, ethnicity, gender, height and weight. A normal GFR ranges from 90 to 120 milliliters per minute per 1.73 square meters.

The glomerular filtration rate, also called eGFR or Estimated GFR, estimates the volume of blood passing through tiny filters in the kidney each minute, according to MedlinePlus. The normal range for GFR is approximately 90 to 120 milliliters per minute per 1.73 meters squared.

The tiny kidney filters, known as glomeruli, filter the blood more slowly in a person with chronic kidney disease. This slow filtration causes a GFR that is consistently below normal.

Doctors suspect chronic kidney disease if a patient's GFR is less than 60 for 3 months or more, according to MedlinePlus. A GFR less than 15 usually indicates kidney failure and requires prompt medical care. Patients should inform their doctor if they are pregnant, or taking antibiotics or medications to control stomach acid, because these factors can affect GFR.