Low eGFR: Should You Worry?
Published Aug 2026 · Reading time: 4 minutes
The short answer:A mildly low eGFR — roughly 60–89 — is common and usually not a kidney-disease verdict. Dehydration, a big workout, protein-heavy meals, and certain medications can all nudge it down. The standard next step is simple: drink normally, retest in a few weeks, and let your doctor look at eGFR together with your creatinine and a urine check. A value below 60 on repeated tests is the number doctors actually take seriously.
First, what is eGFR?
eGFR (estimated glomerular filtration rate) is a calculated estimate of how well your kidneys filter waste. It's not measured directly — the lab computes it from your creatinine, your age, and your sex. Think of it as a score out of about 100+: above 90 is usually called normal, and the number naturally slides down a little with age.
Because it's an estimate built on creatinine, anything that moves creatinine also moves eGFR. That's the key to why one low reading is so often a false alarm.
Where your number sits
🟢 90+: Considered normal filtering. No action needed unless your doctor sees something else.
🟡 60–89: The "mildly reduced" zone. Very common, especially with dehydration or in people with more muscle. The plan is retest — not panic. Most people in this zone do not have progressive kidney disease.
🔴 Below 60, repeated: This is the threshold doctors use for chronic kidney disease staging — but it must be confirmed on repeat tests over 3+ months, together with urine findings. One isolated value is not a diagnosis.
Why a single low eGFR is often a false alarm
- Dehydration. Less water in your blood concentrates creatinine, which drags the eGFR estimate down. This is the #1 everyday cause of a "low" eGFR.
- Muscle. Creatinine comes from muscle. Athletic people and muscular builds run higher creatinine and therefore a lower calculated eGFR — even with perfectly healthy kidneys.
- Recent hard workout. Intense exercise temporarily raises creatinine for a day or two.
- Protein-heavy meals or supplements. Big meat meals and creatine supplements can lift creatinine before a draw.
- Medications. Some blood-pressure drugs (ACE inhibitors, ARBs) and common painkillers (NSAIDs like ibuprofen) can shift creatinine — usually reversibly.
Your follow-up plan
Drink water normally for a couple of days, avoid an intense workout for 48 hours before the draw, and repeat the test in 2–4 weeks. Ask your doctor to order the retest with a urine check — the combination of eGFR trend plus urine findings (protein, blood) is what actually tells you whether your kidneys need attention.
Book a doctor visit sooner if your eGFR is clearly below 60, or if you notice swelling in your ankles, foamy urine, or blood in your urine.
What to do next
Don't treat one number as a diagnosis. Do: retest, stay normally hydrated, and ask about your creatinine trend — the two numbers are read together. Kidney function changes slowly; a few weeks of observation changes nothing for the worse, but spares you a week of needless worry.
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