Your eGFR estimates how well your kidneys filter waste from your blood, calculated from a blood creatinine level along with your age and sex. An eGFR of 90 or higher is generally considered normal kidney function.
| Stage | eGFR (mL/min/1.73m²) | Kidney function |
|---|---|---|
| Normal (G1) | 90 or higher | Normal |
| G2 | 60 to 89 | Mildly reduced |
| G3 | 30 to 59 | Moderately reduced |
| G4 | 15 to 29 | Severely reduced |
| G5 | Below 15 | Kidney failure |
A single low eGFR is not a diagnosis; chronic kidney disease requires reduced values over at least 3 months. Compare to your own report.
What eGFR measures
eGFR estimates the volume of blood your kidneys filter each minute, standardized to body size. It is not measured directly but calculated from your serum creatinine, age, and sex using a validated equation. Because creatinine reflects muscle metabolism, the estimate stands in for the true filtration rate.
What high or low levels mean
A low eGFR points to reduced filtering capacity. It can reflect chronic kidney disease, but a temporary dip may also come from dehydration, certain medications, or an acute illness, and values naturally decline with age. A high or normal eGFR (90 or higher) generally signals healthy filtration, and there is no meaningful concern about eGFR being too high. Keep in mind the number is estimated: greater muscle mass raises creatinine and can nudge your eGFR lower, while low muscle mass can make it read higher than your kidneys truly perform. Follow up with a clinician if your eGFR stays below 60 across repeat tests, drops suddenly, or comes with protein in your urine.
eGFR FAQ
Can eGFR go back up?
Yes. If a low result stems from dehydration, a short-term illness, or a medication effect, your eGFR often recovers once the cause is addressed. Filtration lost from long-standing chronic damage is usually harder to reverse.
Why is eGFR estimated instead of measured?
Directly measuring filtration requires specialized testing that is impractical for routine care. Estimating it from a standard creatinine blood test, plus your age and sex, gives a reliable, low-cost approximation for most people. Read alongside your creatinine, blood urea nitrogen, and uric acid results for a fuller view of kidney health.
References
- National Kidney Foundation. Estimated Glomerular Filtration Rate (eGFR) and Kidney Disease Stages.
- National Kidney Foundation. CKD Stages G1 to G5.
