eGFR: What Your Kidney Filtration Number Really Means (Without the Panic)

What eGFR Actually Measures (In Normal-People Language)

eGFR stands for Estimated Glomerular Filtration Rate.
Basically, it’s an estimate of how well your kidneys are filtering waste from the blood.

Key word?
Estimated.
This number is not exact — it’s based on a formula using your creatinine level, age, sex, and sometimes race.

So yes — the number can shift around based on things that have nothing to do with kidney damage.

Think of eGFR like your car’s gas mileage estimate.
It tells you something useful…
but it’s not the whole story.

Why eGFR Matters

Your kidneys do a LOT for you:

• filter waste

• balance electrolytes

• keep blood pressure stable

• regulate water balance

• activate vitamin D

• support hormone balance

So when eGFR drops, it’s a sign your filtration might be slowing.

But — and I want you to remember this:

A single low eGFR means nothing without context.

Hydration, stress, medications, muscle mass, sleep, illness, and aging all impact this number.

This is why I always look for patterns over time instead of stressing over one result.

Understanding Your Numbers

These ranges are general — your lab may differ slightly.

Normal / Optimal

90–120
(Healthy adult kidney filtration)

Age-related decline (not necessarily disease)

60–89
Very common after age 40.
Very common in postpartum women.
Very common during stress or dehydration.

Potential Kidney Disease (if persistent for 3+ months)

<60
This is when we start paying closer attention.

Significant Kidney Stress

<45
Often needs specialist care, especially with symptoms.

Severe Reduction

<30
Higher level monitoring required.

And here’s an important truth:

Women almost always have lower eGFR than men because we have lower muscle mass.

So your “normal” and your husband’s “normal” are not comparable.

Why eGFR Can Look Low Even If Your Kidneys Are Fine

Ohhhh, buckle up — because this explains SO many confusing labs.

1. You were dehydrated.

Even mild dehydration makes eGFR drop.

2. You didn’t sleep well.

Poor sleep → elevated cortisol → reduced kidney blood flow → lower eGFR.

3. You’re stressed.

Stress constricts blood vessels, reducing filtration temporarily.

4. You exercised the day before.

Muscle breakdown increases creatinine, which lowers eGFR.

5. You have more or less muscle than average.

Muscle mass impacts creatinine → impacts eGFR.

6. You had a viral illness.

Kidneys respond strongly to inflammation.

7. You’re over 40.

It is normal for filtration to slowly decline with age.

This is why I always say:

eGFR is not a personality test. It’s a trend.

One “off” result ≠ disaster.

When eGFR Does Matter

Persistent eGFR below 60 for three months or more tells us your kidneys need more support and monitoring — especially if paired with:

• swelling in the feet or ankles

• foamy urine

• high blood pressure

• fatigue

• shortness of breath

• abnormal potassium or sodium levels

• abnormal creatinine

But again: we’re looking for trends, not a single snapshot.

How to Support Healthy Kidney Filtration (Without Overhauling Your Life)

Kidneys love simplicity and consistency:

1. Stay hydrated — throughout the day, not all at once.

Your kidneys prefer steady flow.

2. Balance your blood sugar.

High glucose slowly damages filtration over time.

3. Prioritize sleep.

Repair processes happen at night.

4. Move your body daily.

Even light activity improves renal blood flow.

5. Limit NSAID overuse.

Ibuprofen is not your kidney’s best friend.

6. Keep blood pressure in range.

Your kidneys and cardiovascular system are deeply connected.

7. Manage stress.

Calm nervous system → better circulation → happier kidneys.

None of this needs to be perfect — just consistent.