The GFR medical abbreviation stands for glomerular filtration rate, the amount of blood the kidneys filter each minute. It is the main number clinicians use to describe how well the kidneys are working, and on most lab reports it appears as eGFR, the e meaning estimated.
The result is calculated from a creatinine blood test, usually part of a BMP or CMP, along with age and sex. It is reported in milliliters per minute adjusted to an average body size. Higher numbers mean better filtering. The sections below cover reading the number, what the kidney stages mean, and why one result is never the whole story.
At a glance
Stands for
Glomerular filtration rateWritten as
GFR, eGFR, est GFRUnits
mL/min/1.73 m², milliliters per minute per standard body surfaceNormal range
Usually 90 or above in healthy young adults; falls slowly with ageBased on
Creatinine, sometimes cystatin C, plus age and sexDo not confuse with
CrCl (creatinine clearance) and BUN
What glomerular filtration rate means
A kidney contains roughly a million tiny filters called glomeruli. Blood flows through them, and water, salts and waste pass into the start of the urine while blood cells and most proteins stay behind. The filtration rate is the total volume of fluid those filters process each minute. When the kidneys are damaged, fewer filters work, and the rate drops.
The word glomerulus comes from Latin for a small ball of yarn, which is what these looped clusters of tiny vessels look like under a microscope.
Measured GFR versus estimated eGFR
Measuring true filtration is slow and involves injecting a special marker and collecting timed samples, so it is used mainly in research and special cases. Day to day, labs estimate it. A formula takes the creatinine level, a waste product from muscle, and adjusts for age and sex. Newer equations used in the United States no longer include race. Some labs also use cystatin C, another blood marker, which is less affected by muscle mass.
Because creatinine depends on muscle, the estimate can mislead in people with very high or very low muscle mass, during pregnancy, or when kidney function is changing quickly, such as in AKI.
GFR stages in chronic kidney disease
Chronic kidney disease is staged partly by GFR. A value below 60 that lasts three months or more, or signs of kidney damage such as protein in the urine, meets the definition of CKD.
| Stage | GFR (mL/min/1.73 m²) | Plain description |
|---|---|---|
| G1 | 90 or higher | Normal or high |
| G2 | 60 to 89 | Mildly decreased |
| G3a | 45 to 59 | Mildly to moderately decreased |
| G3b | 30 to 44 | Moderately to severely decreased |
| G4 | 15 to 29 | Severely decreased |
| G5 | Below 15 | Kidney failure |
A G2 value with no other signs of kidney damage is common in older adults and is not, by itself, kidney disease.
Reading a GFR line in a report
A primary care note: "eGFR 52, down from 61 last visit. Urine albumin pending. Repeat BMP in 3 months." The estimated filtration rate has dropped into the G3a range. The clinician is checking urine protein and repeating the blood test to see whether the change lasts, since CKD needs a stable pattern over months.
Lab portals often show a result as "greater than 60" or "greater than 90" rather than an exact number. Many labs report it that way because the formula is less precise at higher values.
Why the GFR medical abbreviation matters for medicines
Many medicines leave the body through the kidneys, so pharmacists and prescribers look at the filtration rate when choosing a dose. Some antibiotics, blood thinners, diabetes medicines such as metformin, and contrast dye for scans are adjusted or avoided when the number is low. This is a decision for the prescriber and pharmacist. If you see a lower result on your portal, bring it up at your next visit rather than changing anything on your own.
Frequently asked questions
What is a normal GFR?
In healthy young adults it is usually 90 or higher. It tends to drift down slowly with age, so many older adults without kidney disease have values in the 60s to 80s.
What is the difference between GFR and eGFR?
GFR is the true filtration rate, which is hard to measure directly. eGFR is an estimate calculated from a blood test, usually creatinine, and it is what most lab reports show.
Can GFR go back up?
It can, especially if the drop came from dehydration, a short illness or a medicine. In long standing kidney disease the goal is often to slow further decline. Your kidney team can say which applies to you.
Does a GFR under 60 mean kidney disease?
Not from one test alone. Chronic kidney disease means a value under 60 for three months or more, or other signs of kidney damage. A single low result is usually repeated.