Kidney health · 6 min read
What is a dangerous eGFR level?
The short answer: an eGFR below 15 signals kidney failure and is the most dangerous range, while 15–29 (stage G4) is severely reduced and needs urgent specialist care. Any eGFR under 60 that persists for three months or more defines chronic kidney disease and deserves medical attention — but a single low number is a prompt to recheck, not a diagnosis. Here's how to read your result.
Last updated April 15, 2026.
eGFR ranges, from normal to dangerous
eGFR (estimated glomerular filtration rate) estimates how many millilitres of blood your kidneys filter each minute. Higher is better. The KDIGO staging system divides it into bands:
| eGFR | Category | What it means |
|---|---|---|
| 90+ | Normal | Healthy kidney function (unless other damage present) |
| 60 – 89 | Mildly decreased | Usually fine unless albuminuria or other damage present |
| 45 – 59 | Stage G3a | Monitor; not an emergency |
| 30 – 44 | Stage G3b | Closer monitoring, often a nephrology referral |
| 15 – 29 | Stage G4 — severe | Urgent specialist care; plan ahead |
| Below 15 | Stage G5 — kidney failure | Most dangerous; dialysis or transplant |
Why "dangerous" depends on more than the number
Two people with the same eGFR can face very different risk. Doctors read your eGFR alongside your albuminuria (protein in the urine), the trend over months, your age, and the cause. A stable eGFR of 55 in an older adult with no protein in the urine is far less worrying than a 55 that fell from 80 last year with rising albuminuria. That's why context — not a single cut-off — decides how urgent a result is.
When a low reading may not be real kidney disease
eGFR can dip temporarily and then recover. Common reversible causes include dehydration, a recent high-protein meal, intense exercise, contrast dye from a scan, and medicines such as NSAIDs (ibuprofen), ACE inhibitors, or ARBs. Because of this, chronic kidney disease is only diagnosed when the abnormality persists for at least three months. A single surprising result should be repeated before any conclusions are drawn.
Warning signs to take seriously
Early kidney disease is usually silent. As function drops into the severe range, watch for:
- Swelling in the legs, ankles, or around the eyes
- Persistent fatigue, poor appetite, or nausea
- Trouble concentrating or unusual drowsiness
- Itchy skin, muscle cramps, or changes in how much you urinate
These are non-specific and have many causes — the point is to get checked promptly rather than to self-diagnose.
Frequently asked questions
What eGFR level is dangerous?+
An eGFR below 15 mL/min/1.73m² signals kidney failure (stage G5) and is the most dangerous range — dialysis or a transplant is usually needed. An eGFR of 15–29 (stage G4) is severely decreased and needs specialist nephrology care. Below 60 that persists for three months or more defines chronic kidney disease and warrants medical review.
Is an eGFR of 45 or 50 dangerous?+
An eGFR of 45–59 is stage G3a — mildly to moderately decreased. It is not an emergency, but it does mean your kidneys are working below normal and should be monitored, with attention to blood pressure, blood sugar, and medications. Whether it's concerning depends on your albuminuria, the trend over time, and your overall health.
Can a low eGFR go back to normal?+
Sometimes. If the drop was caused by something reversible — dehydration, a short course of NSAIDs, contrast dye, or an acute illness — eGFR often recovers once the cause is corrected. Damage from long-standing (chronic) kidney disease is usually not reversible, but its decline can be slowed considerably with treatment.
What are the warning signs of dangerously low kidney function?+
Early kidney disease often has no symptoms. As eGFR falls into the severe range, possible signs include swelling in the legs or around the eyes, fatigue, poor appetite, nausea, trouble concentrating, itchy skin, and changes in urination. These are non-specific — see a clinician promptly rather than self-diagnosing.
Estimate your eGFR and see your KDIGO stage with the CKD-EPI 2021 calculator.
For general education only. Not medical advice or a diagnosis. If you have a low eGFR or symptoms, contact a qualified healthcare professional. References: KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney Int. 2024; National Kidney Foundation; National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).