You’ve probably heard of cholesterol, glucose, and maybe even liver enzymes in your blood test. But then there’s eGFR—a number that may not get as much attention, yet plays a crucial role in monitoring your overall health, especially your kidneys.
If you’re wondering what is eGFR in blood work, you’re asking an important question. This little acronym stands for something that can tell you how well your kidneys are functioning—and whether they might need a little more care than you realized.
What does eGFR stand for?
eGFR stands for estimated Glomerular Filtration Rate. It’s a calculated value based on a blood test for creatinine, which is a waste product your body makes when muscles break down protein.
Your kidneys filter creatinine (and many other substances) from the blood. The eGFR uses the creatinine level, along with your age, sex, and sometimes race, to estimate how much blood your kidneys filter per minute. This is measured in milliliters per minute per 1.73 m² of body surface area.
Put simply: the eGFR tells you how efficiently your kidneys are doing their job.
Why is eGFR important?
The kidneys are your body’s filtration system. They clean your blood, remove waste and excess fluids through urine, help regulate blood pressure, produce hormones, and maintain the right balance of electrolytes.
When the kidneys start to decline in function, you might not feel it at first. That’s why a low or declining eGFR can be one of the earliest signs of chronic kidney disease (CKD)—even before symptoms appear.
Doctors monitor eGFR to:
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Detect early kidney damage
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Track changes over time
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Decide when treatment or lifestyle changes are needed
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Adjust medications that are cleared through the kidneys
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Plan for further testing if needed
What is a normal eGFR?
In healthy individuals:
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Normal eGFR = 90 or above
That doesn’t mean everyone with an eGFR below 90 has kidney disease. Here’s a general breakdown:
| eGFR (mL/min/1.73 m²) | Stage | What it means |
|---|---|---|
| 90 or above | Normal or high | Healthy kidney function |
| 60–89 | Mild decrease | Often normal with age, monitor if stable |
| 45–59 | Stage 3A CKD | Mild to moderate loss |
| 30–44 | Stage 3B CKD | Moderate to severe loss |
| 15–29 | Stage 4 CKD | Severe loss, possible symptoms |
| Below 15 | Stage 5 CKD or kidney failure | Requires specialist care |
Note that eGFR naturally declines with age. A 70-year-old with an eGFR of 65 might be perfectly healthy. However, if the number drops steadily over time, it becomes more concerning.
What causes low eGFR?
A lower-than-normal eGFR usually means your kidneys are not filtering as efficiently. Common causes include:
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Chronic kidney disease – often due to diabetes or high blood pressure
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Acute kidney injury – sudden kidney stress from dehydration, infection, or medications
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Glomerulonephritis – inflammation of the kidney’s filtering units
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Polycystic kidney disease – an inherited disorder
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Autoimmune diseases – such as lupus
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Obstruction – like kidney stones or enlarged prostate
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Long-term use of certain drugs – NSAIDs (like ibuprofen), some antibiotics, or contrast dye
Sometimes a temporarily low eGFR is due to dehydration or a short-term illness and resolves on its own.
Can eGFR be too high?
Not exactly. A value over 90 is typically considered good. In some cases, however, very high filtration (hyperfiltration) may be seen in early diabetic kidney disease—but this is something your doctor would interpret in context with other tests.
How is eGFR different from creatinine?
Both are related, but they aren’t the same.
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Creatinine is the raw value measured in your blood.
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eGFR is a calculation that uses your creatinine level (plus age, sex, and sometimes race) to estimate actual kidney function.
That’s why a creatinine level of 1.2 mg/dL may be normal for one person but signal a problem in someone else, depending on their body size and age. eGFR adjusts for those differences and gives a more personalized estimate of kidney function.
What should you do if your eGFR is low?
If your eGFR is slightly low and stable:
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Your doctor may monitor it periodically
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You might be advised to stay hydrated, eat a kidney-friendly diet, and manage blood pressure and blood sugar
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Some medications might need to be adjusted
If it’s significantly reduced:
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Additional tests (like urinalysis, renal ultrasound, or urine albumin) may be done
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Referral to a nephrologist (kidney specialist) may be considered
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You might be advised to limit salt, protein, and phosphorus intake
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Lifestyle changes become even more important
The goal is to slow down progression, prevent complications, and maintain quality of life.
In rare cases, if kidney function continues to decline, treatment options like dialysis or transplant evaluation may be discussed—but that’s usually much further down the road.
Your kidneys are resilient organs, and many people live full, healthy lives even with mild to moderate kidney disease—as long as they know what’s going on and take care of their health.
Knowing your eGFR is like reading a small but powerful message from your body. It doesn’t tell the whole story on its own, but when combined with the right information and medical guidance, it gives you the chance to protect one of your most important systems before symptoms ever begin.