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eGFR and Kidney Health
eGFR and Kidney Health: What Your Test Result Really Means
Worried about your kidney health? Your eGFR number could tell you more than you think.
The estimated glomerular filtration rate (eGFR) is one of the most essential blood tests used to check how well your kidneys are working. Recommended by the National Kidney Foundation, this test helps detect early signs of chronic kidney disease (CKD) often before symptoms start.
In this article, we’ll walk you through what your eGFR means, how it’s calculated, the stages of chronic kidney disease, and what to do if your test results show that your kidneys may not be working as they should.
What Is eGFR and How Does It Relate to Kidney Function?
eGFR (“estimated glomerular filtration rate”) is a key number that reflects how well your kidneys filter your blood by removing waste products like creatinine.
The glomeruli are tiny filters in your kidney that clean your blood and remove toxins through your urine. A low eGFR can be one of the first signs of kidney damage, even if you don’t feel sick. That’s why it’s considered a core measure of how well your kidneys are working.
How Is the eGFR Test Performed?
The eGFR test is based on a simple blood test, and is usually part of routine lab panels. The test measures the amount of creatinine in your blood, and the calculator uses the CKD-EPI formula (from 2009 or the newer 2021 version) to estimate GFR.
Because creatinine is a waste product, levels rise when kidneys are not working well. The test is also influenced by age, sex, and muscle mass, which is why formulas are used to adjust for these variables.
What Do eGFR Levels Mean in a Blood Test Result?
Your eGFR number helps your doctor determine the stage of kidney disease you’re in. Here’s a breakdown of the five stages:
| eGFR Range | Stage of CKD | What It Means |
|---|---|---|
| 90+ | Stage 1 | Normal eGFR with possible damage |
| 60–89 | Stage 2 | Mild loss of kidney function |
| 30–59 | Stage 3 | Moderate loss—kidney disease is getting worse |
| 15–29 | Stage 4 | Severe loss; close monitoring needed |
| <15 | Stage 5 | Kidney failure; may need dialysis or a kidney transplant |
Why Creatinine Matters: Understanding Your Blood Test Results
Creatinine in your blood reflects how well your kidneys clean your blood by removing this waste product. High creatinine levels mean your kidneys are not filtering properly, reducing your eGFR.
Factors that affect creatinine blood test results include:
- Muscle mass
- Dehydration
- Certain medications
- Use of supplements
Discuss any unusual factors with your health professional to help them interpret your blood test results correctly.
What Happens if My eGFR Is Low?
A low eGFR doesn’t always mean your kidneys are failing, but it’s a warning sign. Your doctor will check other tests to confirm how much kidney damage there is. You may be referred to a nephrologist (a kidney doctor) to identify the cause of your kidney disease and recommend early steps to protect your kidney health.
In later stages, treatments may include lifestyle changes, medications, and preparing for dialysis or a kidney transplant.
What Can You Do to Support Healthy Kidneys?
If your eGFR is declining, focus on protecting what you still have. Here are proven tips to support healthy kidneys:
- Reduce sodium, sugar, and ultra-processed foods
- Stay well-hydrated
- Avoid smoking and excessive alcohol
- Keep blood pressure in the normal range
- Discuss medications with your doctor to avoid kidney damage
What Other Tests Should I Take to Check My Kidney Health?
Alongside the eGFR test, your doctor may recommend:
- A creatinine clearance test
- A urine test for albumin or protein in your urine
- A blood creatinine test
- Imaging like a kidney ultrasound
These tests to check your kidney function help provide a full picture, especially for people with kidney conditions or those at high risk.
Summary: Understanding Your eGFR Number
- eGFR is a test that measures how well your kidneys are working
- It’s calculated using a formula based on a sample of your blood
- A low eGFR may indicate kidney disease is getting worse
- Doctors use eGFR to determine what stage of kidney disease you’re in
- Always discuss your test results with a health professional to understand the next steps
Further References
- National Kidney Foundation. Kidney Failure Risk Factor: Estimated Glomerular Filtration Rate (eGFR) [Internet]. Kidney.org. 2024. Available from: https://www.kidney.org/kidney-failure-risk-factor-estimated-glomerular-filtration-rate-egfr
- NHS . Chronic kidney disease [Internet]. NHS. 2023. Available from: https://www.nhs.uk/conditions/kidney-disease/
- Aeddula N. Chronic kidney disease [Internet]. National Library of Medicine. StatPearls Publishing; 2024. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535404/
- NIDDK. Chronic Kidney Disease (CKD) [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases. 2019. Available from: https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd
Disclaimer: This article is for educational purposes only. Please consult your healthcare provider for personalized recommendations.
