eGFR Explained: Quick Guide to Kidney Function and Health

When your doctor mentions eGFR, they’re talking about a number that tells how well your kidneys are filtering blood. It stands for estimated Glomerular Filtration Rate, and it’s the go‑to metric for checking kidney health without an invasive test.

eGFR is calculated from your serum creatinine level, age, sex, and sometimes race. The formula gives a value in milliliters per minute per 1.73 m² of body surface. In plain terms, it estimates how many milliliters of blood your kidneys clear each minute.

What’s a Normal eGFR?

For most healthy adults, an eGFR of 90 ml/min/1.73 m² or higher is considered normal. Values between 60 and 89 are usually fine if you have no other signs of kidney disease. Once the number drops below 60, doctors start looking for chronic kidney disease (CKD). Below 30, the kidneys are severely impaired, and you may need specialized care or dialysis.

These ranges aren’t set in stone. Muscle mass, diet, and certain medications can push the number up or down temporarily. That’s why doctors often repeat the test and consider other clues before diagnosing a problem.

Factors That Can Change Your eGFR

Dehydration is a quick way to lower eGFR because less fluid means less blood flow to the kidneys. High blood pressure and uncontrolled diabetes are long‑term culprits that slowly erode kidney function. Certain drugs—like NSAIDs, some antibiotics, and contrast dyes—can also cause a temporary dip.

Age matters, too. As you get older, eGFR naturally declines about one point per year. That’s why a 70‑year‑old with an eGFR of 65 might be perfectly healthy, while a 30‑year‑old with the same number would need further evaluation.

Keeping an eye on your eGFR is especially useful if you have a family history of kidney disease, take kidney‑impacting meds, or have conditions that strain the kidneys.

How to Support a Healthy eGFR

Stay hydrated—aim for at least 8 glasses of water a day unless your doctor says otherwise. Control blood pressure and blood sugar; both are proven to slow kidney damage. Limit high‑protein or high‑salt meals if you already have reduced kidney function, because excess waste products can burden the kidneys.

Exercise regularly. Even moderate activity like brisk walking improves circulation and helps maintain a healthy weight, which eases the workload on your kidneys. Avoid overusing over‑the‑counter pain relievers such as ibuprofen or naproxen; they can cut blood flow to the kidneys.

If you’re on prescription meds that affect kidney health, ask your pharmacist or doctor about monitoring eGFR during treatment. Adjusting the dose or switching drugs can keep the number stable.

Finally, schedule routine blood tests if you’re at risk. Spotting a dip early lets you and your doctor take steps before permanent damage sets in.

Remember, eGFR is just one piece of the puzzle, but it’s a powerful indicator you can use to stay ahead of kidney issues. Keep track, stay active, and talk to your healthcare provider about any changes—you’ll give your kidneys the best chance to keep working smoothly.