If you are asking what is eGFR in blood test results, the short answer is a kidney score. eGFR stands for estimated glomerular filtration rate: an estimate of how many milliliters of blood your kidneys filter each minute, calculated from the creatinine on your metabolic panel along with your age and sex. A value of 90 or above is normal. Under 60, confirmed over three months, is chronic kidney disease. It is an estimate, which is why one low result is never the final word.

Where it comes from

eGFR is not something the lab measures directly. It is worked out from creatinine, a waste product your muscles make at a steady rate and your kidneys clear. When the kidneys filter less, creatinine builds up in the blood, and the eGFR calculation falls.

Since 2021, US labs have used the race-free CKD-EPI equation, which takes creatinine, age, and sex and nothing else. The National Kidney Foundation led that change, and you can run the same calculation yourself on its eGFR calculator if you have your creatinine value. The number is reported per 1.73 square meters of body surface, which lets results be compared between people of different sizes.

Finding eGFR in blood test results is easy. It sits next to creatinine on any comprehensive or basic metabolic panel and on every kidney panel. Our eGFR test guide covers the full test.

What is eGFR in blood test results, exactly?

It is a stage marker. Kidney doctors divide eGFR into bands that describe how much filtering capacity remains.

Ninety and above is normal. Sixty to 89 is mildly reduced, which is common with age and usually not significant on its own. Forty-five to 59 is mild to moderate reduction. Thirty to 44 is moderate to severe. Fifteen to 29 is severe. Under 15 is kidney failure, the range where dialysis or transplant is discussed.

Two things decide whether a reduced number means kidney disease. The first is time: chronic kidney disease is defined as an eGFR under 60 on two tests at least three months apart, or any eGFR with signs of kidney damage such as protein in the urine. The second is the rest of the picture. A single value of 58 in a well-hydrated person with normal urine is a prompt to recheck, not a diagnosis.

This matters because kidney disease is almost always silent until late. The National Kidney Foundation estimates that 37 million US adults have it and about 90 percent do not know. The number on a routine panel is usually how they find out.

When the number is wrong

Because eGFR is calculated from creatinine, anything that changes creatinine without touching the kidneys changes eGFR too. That is the honest answer to what is eGFR in blood test reports: a good estimate with known blind spots.

It reads falsely low in people with a lot of muscle, in anyone taking creatine supplements, after a heavy workout, after a large meat meal, and when dehydrated. It reads falsely high in people with low muscle mass, including older adults, people who are malnourished, and those with liver disease. The equation is also not validated in pregnancy or under age 18, as Michigan Medicine's lab notes on its reporting.

When a result does not fit the person, clinicians reach for cystatin C, a second filtration marker that does not depend on muscle. An eGFR calculated from creatinine and cystatin C together is more accurate than either alone. Our creatinine test guide explains the marker underneath all of this.

What to do with a low result

People searching what is eGFR in blood test results have usually just seen one flagged. The sequence that follows is the same almost every time.

First, repeat the test, well hydrated, without hard exercise or creatine in the days before. A low eGFR in blood test reports is confirmed before anyone calls it kidney disease.

Second, add a urine albumin-to-creatinine ratio. Protein leaking into urine is the earliest sign of kidney damage, and it can be present while eGFR is still normal.

Third, look at the causes. Diabetes and high blood pressure account for most chronic kidney disease. Regular NSAID use, some blood pressure medicines in the wrong setting, and a family history matter too.

Fourth, slow it down. Controlling blood pressure and blood sugar, avoiding NSAIDs, and in many cases a medication class called SGLT2 inhibitors can hold eGFR steady for years. Early-stage kidney disease progresses slowly in most people when those are in place.

How to get tested

eGFR comes with any comprehensive or basic metabolic panel. August's lab tests include both, plus a kidney panel, at one price that covers the draw. A phlebotomist comes to your home or you visit a nearby lab. Results post the next day in most cases, with eGFR shown against the lab's range and a clinician's review of every result, so a flagged value comes with context rather than a bare number. August Care members get up to 50 percent off next-day lab tests and a first consultation included.

Not sure whether a kidney check is what you need? Describe your symptoms to August, a free AI health assistant, to help decide. It is a starting point, not a diagnosis.

Frequently Asked Questions

It is an estimate of how well your kidneys filter blood, calculated from creatinine, age, and sex, and reported in mL/min per 1.73 m². It appears on every metabolic panel next to creatinine. Ninety or above is normal; under 60 on two tests three months apart defines chronic kidney disease.

Ninety or above. Sixty to 89 is mildly reduced and common with age, and it does not by itself mean kidney disease unless there are other signs such as protein in the urine. Labs print their own cutoffs, and the value declines gradually through adult life even in healthy kidneys.

Yes. High muscle mass, creatine supplements, dehydration, a recent heavy workout, or a large meat meal all raise creatinine and lower the estimate without any change in the kidneys. A repeat test under better conditions, or a cystatin C test, usually sorts it out.

Mildly reduced, in the 60 to 89 band. For most adults over 40 this is within the expected range and is not treated as disease unless urine tests show kidney damage. A clinician will typically recheck it at the next routine panel rather than act on it.

No. It is calculated from creatinine, which is not affected by meals in the short term. It is often drawn with a fasting metabolic panel because glucose on the same panel needs fasting. Avoid heavy exercise the day before and stay hydrated.

Creatinine is the measured value. eGFR is calculated from it, adjusted for age and sex, so that it reflects filtering capacity rather than a raw concentration. Two people with the same creatinine can have different eGFRs if one is older or female.

A second kidney filtration marker that is not affected by muscle mass or diet. It is used alone or combined with creatinine when a creatinine-based eGFR does not match the clinical picture, and the combined equation is more accurate than either marker alone.

Yes. An August phlebotomist draws the sample at home, and eGFR is reported with the metabolic or kidney panel the next day in most cases, shown against the lab's range with a clinician's review. Hydrate beforehand and skip hard exercise the day before for the most reliable reading.