What does eGFR measure?
Your kidneys contain millions of tiny filters that clean your blood and make urine. eGFR estimates how much blood those filters clean each minute. It is calculated from a blood test that measures a waste product called creatinine, together with your age and sex.
The result is given as a number 'per 1.73 m²' (a standard body size), with most labs reporting anything above 90 simply as '90 or more'.
What is a normal eGFR?
In a healthy young adult, eGFR is usually around 100. It naturally falls a little with age. An eGFR of 90 or above, or 60–89 without any other sign of kidney damage, is generally considered normal.
A single low reading does not necessarily mean kidney disease — it can be affected by dehydration, some medicines, or a recent meal. Doctors usually look at the trend over time and repeat the test.
What do the numbers mean? (CKD stages)
If kidney function is reduced, doctors describe it in stages, from G1 (normal) to G5 (kidney failure): G1 is 90 or above, G2 is 60–89, G3a is 45–59, G3b is 30–44, G4 is 15–29, and G5 is below 15.
Many people with early-stage reduced kidney function feel completely well and never go on to have serious problems, especially if blood pressure and diabetes are well controlled.
What happens next?
If your eGFR is low, your doctor may repeat the blood test, check your urine for protein, review your blood pressure and medicines, and sometimes arrange a scan. The aim is to find any treatable cause and to protect your kidneys.
The most important things you can usually do are keep blood pressure and blood sugar well controlled, stay well hydrated, avoid smoking, and take medicines only as advised — some painkillers and supplements can affect the kidneys.
Common questions
Is a low eGFR dangerous?
Not necessarily. Mildly reduced eGFR is common, especially with age, and many people remain well. A very low or rapidly falling eGFR needs medical attention. Your doctor will interpret your result alongside your overall health.
Can eGFR improve?
Sometimes, yes — for example if a low reading was caused by dehydration or a temporary illness. Long-standing kidney damage is often stable rather than reversible, but the right care can slow or stop it getting worse.
What is the difference between eGFR and creatinine?
Creatinine is the waste product measured in the blood. eGFR is a calculation that turns the creatinine level (plus your age and sex) into an easier-to-interpret estimate of kidney filtering.
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