eGFR
Also reported as: Estimated glomerular filtration rate · Kidney function · Creatinine clearance
How fast the kidneys filter blood, estimated from serum creatinine together with age and sex. It is a calculation, not a measurement.
Above 90 is normal, 60-89 mildly reduced, below 60 for three months or more defines chronic kidney disease.
Above 90 is the target at any age. A decline of more than about 1 mL/min per year is faster than expected ageing and worth investigating.
Guideline thresholds from: KDIGO chronic kidney disease guideline
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Where the thresholds sit
| Band | Range (mL/min/1.73m²) | Note |
|---|---|---|
| Optimal | > 90 | — |
| Mildly reduced | 60–90 | Common with age; the trend over years matters more than one value. |
| Moderately reduced | 30–60 | Chronic kidney disease if sustained for three months. Needs medical follow-up. |
| Severely reduced | < 30 | Requires specialist care. |
Why it matters
Kidney function declines with age in almost everyone, silently, and reduced eGFR is an independent predictor of cardiovascular events and mortality well before it becomes kidney disease. It also constrains what else you can safely take — a great many drugs and supplements are renally cleared, so this number quietly sets the boundaries of everything else on this site.
What raises it
- Nothing you want — a spuriously high eGFR usually means low muscle mass giving a falsely low creatinine
What lowers it
- Dehydration, temporarily and commonly
- High muscle mass or heavy creatine use — raises creatinine without any change in kidney function
- A large protein or cooked-meat meal before the test
- NSAIDs, taken regularly
- Uncontrolled blood pressure or diabetes, over years
How to move it
- 1Rule out the artefacts first. Dehydration, a hard training session, a steak dinner or creatine supplementation all raise creatinine and drop the estimate without anything being wrong with your kidneys.
- 2If it stays low, ask for cystatin C. It is not affected by muscle mass and resolves most of the ambiguity.
- 3Control blood pressure. It is the single largest modifiable driver of kidney decline.
- 4Cut regular NSAID use.
- 5Stay hydrated and retest before drawing any conclusion from one reading.
What moves this marker
Interventions on this site with evidence behind them for this specific marker. None of them replaces working out why yours is where it is.
What makes a single reading misleading
- Creatinine comes from muscle, so muscular people and creatine users get falsely low eGFR estimates — a genuinely common false alarm in this audience.
- Equally, low muscle mass in older or frail people produces a falsely reassuring eGFR.
- The equations were derived in specific populations and are least accurate at the extremes.
- A single reading means little; the slope over years is the signal.
Sources
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Educational only. Reference ranges are not diagnostic thresholds and this page cannot account for your medical history, medication or symptoms. Discuss any result that concerns you with a qualified clinician. See our medical disclaimer.