What your eGFR kidney test result means

The short answer

• eGFR stands for "estimated glomerular filtration rate." It is an estimate of how well your kidneys filter your blood. The lab calculates it from a creatinine blood test, your age and your sex.
• For most adults, an eGFR of 60 or higher does not, on its own, point to kidney disease. The number drifts down with age. Kidney guidelines ask labs to flag results below 60 as low.
• One low result is not a diagnosis. Chronic kidney disease (CKD) means kidney problems that last at least 3 months. A low eGFR is usually repeated and checked alongside a urine test for albumin, called the UACR.
• Call your clinician promptly if your eGFR is below 30, has dropped sharply from your usual, or comes with symptoms such as making much less urine or new swelling. For chest pain, serious trouble breathing, sudden confusion or a seizure, call 911.

This page is about adults. Children and teenagers are assessed with different equations, so ask the child's clinician about their results.

What the number measures

Your kidneys contain tiny filters that remove waste and extra water from your blood. Measuring that filtering directly takes an injection and several timed blood samples, so it is rarely done. Instead, the lab measures creatinine, a waste product that comes from normal muscle wear and tear and from protein in your diet. Healthy kidneys clear creatinine steadily. When filtering slows, creatinine builds up and eGFR goes down.

In the United States, the National Kidney Foundation and federal kidney researchers recommend the 2021 CKD-EPI creatinine equation for adults. It uses three things: your creatinine level, your age and your sex.

The result is reported in mL/min/1.73 m². In plain terms, that is about how many milliliters of blood your kidneys filter each minute, adjusted to a standard adult body size. Labs round it to a whole number. Some reports show ">60" or ">90" instead of an exact number; that means your result is above that level.

You will usually find eGFR on a basic or comprehensive metabolic panel, near creatinine and BUN (blood urea nitrogen). Understanding Common Laboratory Tests describes those panels, and How to Read and Understand Your Laboratory Report explains reference ranges, "H" and "L" flags, and why trends matter.

Keep in mind that eGFR is an estimate. Even with the most accurate equations, about 1 in 10 estimates is off by more than 30% from a directly measured value. That is why your clinician looks at the pattern over time more than at any single result.

What the ranges mean

Kidney guidelines sort eGFR into six categories, G1 through G5.

eGFR tends to fall with age, even in people without kidney disease. The National Kidney Foundation lists an average eGFR of about 116 for people in their 20s, 93 in their 50s and 75 at age 70 and older. Your clinician weighs your age, your trend and your urine results together.

Why one low result is not a diagnosis

CKD is defined as a problem with kidney structure or function that lasts at least 3 months. Guidelines advise repeating an unexpected low eGFR, or an abnormal urine result, before calling it CKD. A single low number can come from a short-term kidney injury, or from something that changed creatinine for a day or two. Your clinician may also look back at older results to see whether the low number has been there for months.

Change between tests matters too. For people who already have CKD, kidney guidelines treat a fall of more than 20% from one test to the next as more than the usual ups and downs, and worth a closer look.

The other key test: urine albumin (UACR)

Albumin is a protein that belongs in your blood. Healthy kidneys keep almost all of it out of your urine. The urine albumin-to-creatinine ratio (UACR) measures albumin in a single urine sample and compares it with creatinine. Albumin in the urine can be a sign of kidney damage even when your eGFR is 60 or higher. Kidney guidelines advise testing both eGFR and urine albumin in people at risk.

On your report, look for the line with "ratio" in its name, such as "albumin/creat ratio."

Higher numbers mean a higher risk of kidney failure, heart attack and stroke. An abnormal result is usually repeated within 3 to 6 months, because hard exercise in the previous 24 hours, a fever or infection, a urinary tract infection, menstrual or urinary bleeding, or a sudden spike in blood pressure or blood sugar can raise it for a short time. UACR is not the same as the dipstick test in a routine urinalysis.

Who should be tested? If you have diabetes, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) advises getting checked every year. If you have high blood pressure, heart disease or a family history of kidney failure, ask how often you should be tested. Early CKD usually causes no symptoms, and the CDC estimates that about 9 in 10 U.S. adults with CKD do not know they have it.

Things that can shift eGFR for a while

Because eGFR is calculated from creatinine, anything that changes creatinine without changing your kidneys' filtering can move the number.

• Not drinking enough. Dehydration can raise creatinine and lower eGFR.
• Hard exercise. Intense exercise can raise creatinine.
• A meat meal. Cooked meat or fish can raise creatinine for several hours. The international kidney guideline suggests testing at least 12 hours after such a meal; some labs ask you to skip meat for 24 hours.
• Creatine supplements and very high-protein diets can affect creatinine.
• Muscle mass. Creatinine comes from muscle. A lot more muscle than average can make eGFR read lower than your true filtering; much less muscle, as with frailty, a long illness, an amputation or a spinal cord injury, can make it read higher.
• Medicines. A few medicines raise creatinine by slowing how the kidneys release it, without harming filtering. Others can injure the kidneys: NSAID pain relievers such as ibuprofen and naproxen can cause damage, especially in people with kidney disease, diabetes or high blood pressure. Starting certain blood pressure or kidney-protecting medicines (ACE inhibitors, ARBs, SGLT2 inhibitors) can cause a small early dip that guidelines generally do not treat as a reason to stop; clinicians often recheck within a few weeks. Do not stop a prescribed medicine on your own. Ask the prescriber or a pharmacist.
• Other situations. eGFR is less reliable during pregnancy, after age 70, with cirrhosis of the liver and after a past organ transplant.
• Recent illness. Severe vomiting, diarrhea or dehydration can cause a sudden kidney injury.

Before a repeat test:

• Ask whether to fast or avoid meat beforehand, and for how long.
• Drink your usual amount unless you are told otherwise.
• Skip hard workouts the day before.
• Tell the office about every medicine and supplement, including over-the-counter pain relievers, creatine and protein powders.
• Mention any recent illness or fever, and, for a urine test, any menstrual bleeding.
• Use the same lab when you can, so results are easier to compare.

About the race-free equation

Older eGFR equations used race along with age and sex. Including race gave Black patients a higher estimate, which for transplant candidates could delay the start of waiting time. In 2021, a task force of the National Kidney Foundation and the American Society of Nephrology recommended removing race. The 2021 CKD-EPI equation does not use race, NIDDK supports it, and the international kidney guideline says race should not be used to calculate eGFR. No equation is exact: on average, the race-free creatinine equation reads slightly high in people who are not Black and slightly low in Black people, by about 4%. Adding cystatin C narrows those gaps.

What this means for you:

• Labs have been moving to this equation, but not every lab switched at the same time, so it is reasonable to ask your clinician which equation your lab uses. NIDDK advises labs to name the equation on the report and the date of any change.
• If your lab changed equations between two of your tests, part of the difference may come from the formula, not your kidneys.
• If you are Black and on a kidney transplant waiting list, a national policy in effect since January 5, 2023 let transplant programs request restored waiting time for eligible candidates whose wait was delayed by a race-based calculation. Programs had until January 3, 2024 to review their lists. Ask your transplant program whether your waiting time was reviewed.
• The equation uses sex recorded as female or male. If you are transgender or gender-diverse, the American Kidney Fund suggests talking with your clinician about how to get an accurate estimate.

Cystatin C and other ways to check

Cystatin C is a protein made by cells throughout the body. Its blood level is less affected by muscle and diet than creatinine is. Creatinine and cystatin C together give a more accurate estimate than creatinine alone, and kidney guidelines recommend the combined estimate when the creatinine-based eGFR may be off and the number affects decisions, such as medicine doses or a transplant evaluation. It can help if an earlier result was unclear, or if you are older or very muscular. It can be less accurate with untreated thyroid conditions or steroid use, and it is not yet routine everywhere.

When an exact number matters, as before donating a kidney, some centers measure GFR directly with an injected marker and timed blood samples.

When a result needs prompt attention

Contact your clinician the same day if you:

• are making much less urine than usual, or none;
• have new swelling in your legs, ankles or feet, or new shortness of breath;
• have vomiting or diarrhea and cannot keep fluids down, especially if your eGFR is already low.

Call soon, rather than waiting for a routine visit months away, if:

• your eGFR is below 30, the level at which guidelines advise kidney specialist care;
• your eGFR has fallen by more than about 20% from your usual result;
• your UACR is 300 mg/g or higher;
• your report labels a result "critical" and no one has contacted you.

If a result shows up in your patient portal before anyone explains it, send a message or call the office. Using a Patient Portal covers what portals are and are not for.

Questions to ask your clinician

• How does this eGFR compare with my earlier results? Did the lab's equation change in between?
• Could dehydration, exercise, a meat meal, supplements or a recent illness have affected this result?
• Should I repeat the test, and when? How often after that? Do I need a urine albumin (UACR) test?
• Looking at both tests over time, do I meet the definition of CKD? What are my G and A categories?
• Would a cystatin C test give a more accurate estimate for me?
• Do any of my medicines or supplements need a change because of my kidney function?
• What blood pressure and blood sugar goals should I aim for?
• Do I need a sick-day plan for which medicines to pause if I have vomiting, diarrhea or a fever?
• If my eGFR is under 60, has my risk of kidney failure been estimated? Do I need to see a kidney specialist?

A printable kidney test results log can help you track eGFR and UACR across visits and labs.

Related reading on this site

• Understanding Common Laboratory Tests and How to Read and Understand Your Laboratory Report: the panels where eGFR appears, and how to read any lab report.
• High Blood Pressure and Understanding Type 2 Diabetes: two major risk factors for kidney disease.
• Safe Use of Over-the-Counter Medicines, including NSAID pain relievers.
• Diabetes Medications During Illness, on sick-day planning.

Sources

1. Estimated Glomerular Filtration Rate (eGFR) and GFR Tests — MedlinePlus, U.S. National Library of Medicine, last updated September 30, 2026.
2. Creatinine Test — MedlinePlus, U.S. National Library of Medicine, last updated December 5, 2023.
3. Microalbumin Creatinine Ratio — MedlinePlus, U.S. National Library of Medicine, last updated May 27, 2025.
4. Acute kidney failure — MedlinePlus Medical Encyclopedia, review date April 30, 2026.
5. Glomerular Filtration Rate Equations — National Institute of Diabetes and Digestive and Kidney Diseases, last reviewed May 2025.
6. Factors Affecting eGFR Accuracy — National Institute of Diabetes and Digestive and Kidney Diseases, last reviewed May 2025.
7. Chronic Kidney Disease Tests & Diagnosis — National Institute of Diabetes and Digestive and Kidney Diseases, last reviewed October 2016.
8. Managing Chronic Kidney Disease — National Institute of Diabetes and Digestive and Kidney Diseases, last reviewed October 2016.
9. Estimated GFR (eGFR) Test — National Kidney Foundation, last updated February 5, 2026.
10. CKD-EPI Creatinine Equation (2021) — National Kidney Foundation, accessed October 21, 2026.
11. Urine albumin-creatinine ratio (uACR) — National Kidney Foundation, last updated May 1, 2023.
12. Cystatin C — National Kidney Foundation, last updated July 26, 2023.
13. Acute Kidney Injury (AKI) — National Kidney Foundation, last updated February 26, 2024.
14. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease — Kidney Disease: Improving Global Outcomes, published in Kidney International 2024;105(4S):S117–S314.
15. Blood test: eGFR (estimated glomerular filtration rate) — American Kidney Fund, last updated June 30, 2025.
16. Chronic Kidney Disease in the United States — Centers for Disease Control and Prevention, last reviewed March 31, 2026.
17. Implementation notice: Waiting time modifications for candidates affected by race-inclusive eGFR calculations — United Network for Organ Sharing, last updated January 27, 2023.
18. Modify Waiting Time for Candidates Affected by Race-Inclusive Estimated Glomerular Filtration Rate (eGFR) Calculations — Organ Procurement and Transplantation Network, adopted December 5, 2022, accessed October 21, 2026.