What Does eGFR Mean? Your Kidney Function Explained

Your eGFR is one of the most important numbers on your blood test — and one of the least explained. It shows up as a single value with no context, and it is easy to worry when you cannot tell whether your result is reassuring or something to ask about.

Here is what it means for your kidney health, in plain English, so you know what your number is telling you and when it is worth a conversation with your doctor.

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What is eGFR?

eGFR stands for estimated Glomerular Filtration Rate. It measures how well your kidneys filter waste from your blood — think of it as your kidneys’ percentage of normal function. The higher the number, the more effectively your kidneys are doing their job of cleaning your blood.

What your eGFR number means

eGFR is measured in mL/min/1.73m². Roughly speaking, the higher the number, the better your kidneys are filtering. Here’s what the common ranges generally mean:

eGFR 90 or above
Normal kidney function (as long as there are no other signs of kidney damage).
eGFR 60 to 89
Mildly reduced. This is very common and is often normal for your age, especially if nothing else is off.
eGFR 45 to 59
Mild to moderate reduction (sometimes called stage 3a).
eGFR 30 to 44
Moderate to severe reduction (stage 3b). For example, an eGFR of 44 falls here — your kidneys are working, but noticeably below full capacity, and your doctor will usually monitor it and look for a cause.
eGFR 15 to 29
Severe reduction (stage 4).
eGFR Below 15
Kidney failure (stage 5), which needs specialist care.

Important: One low eGFR is not a diagnosis. It can be temporarily low from things like dehydration, a recent illness, or certain medications, and it naturally drifts down a little with age. Doctors usually repeat the test and look at the trend over time — not a single reading — before drawing conclusions.

What affects your eGFR

1Age — eGFR naturally decreases as you get older.
2Muscle mass — more muscle can affect the calculation.
3Race — labs adjust for this in the formula.
4Hydration level — being dehydrated can shift your result.
5Medications like NSAIDs and some antibiotics.

eGFR and creatinine — how they relate

Creatinine is a waste product your kidneys filter out of your blood. Your eGFR is calculated from your creatinine — along with your age and other factors — so the two move in opposite directions. A higher creatinine usually means a lower eGFR, because it suggests your kidneys are not clearing waste as efficiently.

Red flags — when to call your doctor

A single reading rarely tells the whole story, but a few patterns are worth a prompt call to your provider — especially if you also feel unwell. Reach out about:

A new eGFR below 60
A rapid decline from your previous reading
An eGFR below 30
Reduced eGFR combined with protein in your urine

If you have severe symptoms such as chest pain, trouble breathing, fainting or confusion do not wait for a callback — call 911 or go to the nearest emergency room.

Questions to ask your doctor about your eGFR

1What does my current eGFR number mean for my kidney health?
2Has my eGFR changed compared with my previous results?
3Which CKD stage, if any, does my eGFR put me in?
4Could any of my medications be affecting my eGFR?
5What can I do to protect my kidney function from here?
6How often should I have my eGFR rechecked?
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Medical disclaimer: This page is educational and is not medical advice, diagnosis or treatment. Lab results must be interpreted by a licensed healthcare provider who knows your full history. Always follow your provider’s guidance and call 911 in an emergency.

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