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Understanding GFR - A Guide for Patients
What is Glomerular Filtration Rate?
Your glomerular filtration rate (GFR) is a measure of how well
your kidneys are filtering wastes from your blood. Your GFR has been
estimated from a routine measurement of creatinine in your blood.
Creatinine is a waste product formed by the normal breakdown of
muscle cells. Healthy kidneys take creatinine out of the blood and
put it into the urine to leave the body.
When kidneys are not working well, creatinine builds up in the blood.
What does my GFR number mean?
As you get older, the average GFR number drops. However, a low
GFR with a value below 60 suggests some kidney damage has occurred.
This means that your kidneys are not working at full strength.
What are considered average estimated GFR (eGFR)
values for adults?
The table below shows population estimates for mean (average)
estimated glomerular filtration rate (eGFR) by age. These means,
derived from the NHANES III survey of over 10,000 individuals,
demonstrate that eGFR varies across age groups and that kidney
function tends to decline with age. There is no difference between
races or sexes when eGFRs are expressed per meter squared body
Reference Table for Population Mean eGFRs From NHANES III
|Age (Years)||Mean eGFR*|
|20-29||116 mL/min/1.73 m2|
|30-39||107 mL/min/1.73 m2 |
|40-49||99 mL/min/1.73 m2|
|50-59||93 mL/min/1.73 m2|
|60-69||85 mL/min/1.73 m2|
|70+||75 mL/min/1.73 m2|
For diagnostic purposes the NKDEP recommends laboratories report eGFR values above 60 as "> 60 mL/min/1.73 m2,"
not as an exact number.
How important is my GFR number?
Your doctor will use your GFR number as one clue to how well your
kidneys are working. Your doctor will also look at other factors,
- protein (albumin) in your urine
- high blood pressure
Depending on these factors, your doctor may decide that you have
chronic kidney disease. If you have chronic kidney disease,
controlling your diabetes or high blood pressure can help
prevent more damage to your kidneys and other problems like heart
attacks and strokes.
What do my kidneys do?
Healthy kidneys filter your blood. They remove waste and extra
water, which become urine. The wastes in your blood come from the
normal breakdown of active tissues and from food you eat. After your
body has taken what it needs from the food, waste is sent to the
blood. If your kidneys do not remove these wastes,
the wastes build up in the blood and damage your body.
Where can I get more information?
For more information about kidney disease, contact the
National Kidney Disease Education Program at 1-866-454-3639.
Source: NKDEP is sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK),
National Institutes of Health (NIH),
U.S. Department of Health & Human Services (DHHS). Published on December 28, 2005
Adapted by Editorial Staff, October 2007
Last update, August 2008