eGFR (Estimated Glomerular Filtration Rate)
A blood test that estimates how well your kidneys filter waste from your blood. The key marker for kidney function.
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What is eGFR?
eGFR stands for estimated Glomerular Filtration Rate. It measures how much blood your kidneys filter per minute, expressed in mL/min/1.73m².
Rather than being measured directly, eGFR is calculated from your creatinine level, age, sex, and sometimes race. It's the standard way doctors assess kidney function.
Think of it as a percentage of normal kidney function. An eGFR of 90 means your kidneys are working at roughly 90% capacity.
Normal Ranges
| eGFR Value | Kidney Function |
|---|---|
| 90+ | Normal |
| 60–89 | Mildly reduced |
| 45–59 | Mild to moderate reduction |
| 30–44 | Moderate to severe reduction |
| 15–29 | Severely reduced |
| Below 15 | Kidney failure |
A single low reading doesn't necessarily indicate chronic kidney disease. Doctors typically look for sustained low values over 3+ months.
Why It Matters
Early Detection
Kidney disease often has no symptoms until significant damage has occurred. eGFR catches declining function early, when intervention is most effective.
Medication Safety
Many medications are processed by the kidneys. If your eGFR is low, certain drugs may need dose adjustments or should be avoided entirely.
Cardiovascular Connection
Reduced kidney function is strongly associated with increased cardiovascular risk. Tracking eGFR helps monitor overall health, not just kidney health.
What Affects eGFR
Several factors can temporarily affect your eGFR reading:
- Hydration status — Dehydration can lower eGFR
- Recent intense exercise — Can temporarily raise creatinine
- High-protein meals — May affect creatinine levels
- Certain medications — NSAIDs, some blood pressure drugs
How Often to Test
- No risk factors: Every few years as part of routine blood work
- Diabetes or hypertension: Annually
- Known kidney disease: Every 3–6 months or as directed