eGFR Blood Test
What Is eGFR?
Your kidneys contain millions of tiny filters called glomeruli that remove waste products, toxins, and excess water from your bloodstream. The eGFR estimates how much blood these filters clean per minute, measured in milliliters per minute per 1.73 square meters of body surface area. This is written as mL/min/1.73m². It is calculated using your blood creatinine level, age, sex, and race.
A normal eGFR is typically 90 or higher. Values below 60 for three months or more indicate chronic kidney disease. A sudden drop in eGFR suggests acute kidney injury. This could be caused by dehydration, serious infections, reduced blood flow to the kidneys, certain medications like NSAIDs or antibiotics, or blockages in the urinary tract.
Why Test eGFR?
- Detect kidney disease early, often before symptoms appear
- Monitor kidney function if you have diabetes or high blood pressure
- Guide treatment decisions and prevent progression to kidney failure
- Check for medication side effects that may harm your kidneys
- Assess kidney health before starting new treatments or surgeries
- Track recovery after acute kidney injury or infection
Normal eGFR Levels
| Category | Range | Interpretation |
|---|---|---|
| Optimal | Above 90 mL/min/1.73m² | Kidneys are filtering waste effectively and functioning normally |
| Mildly Decreased | 60 to 89 mL/min/1.73m² | May be normal for older adults but warrants monitoring |
| Moderately Decreased | 30 to 59 mL/min/1.73m² | Indicates moderate kidney impairment requiring medical attention |
| Severely Decreased | 15 to 29 mL/min/1.73m² | Severe kidney disease requiring close monitoring and treatment |
| Kidney Failure | Below 15 mL/min/1.73m² | Kidneys are failing and dialysis or transplant may be needed |
Symptoms of Abnormal eGFR
Symptoms of low eGFR and reduced kidney function include fatigue, swelling in the feet and ankles, puffiness around the eyes, decreased urine output or foamy urine, difficulty concentrating, poor appetite, nausea, itching, muscle cramps, high blood pressure, and shortness of breath. In acute kidney injury, symptoms may come on suddenly. These include confusion, severe fatigue, and significant changes in urination.
High eGFR is rarely symptomatic and usually does not indicate a health problem. When hyperfiltration occurs in early diabetes, there are typically no noticeable symptoms. However, it may be a sign that blood sugar control needs attention to prevent future kidney damage.
What Affects eGFR Levels
Root-cause medicine emphasizes protecting kidney health through hydration, blood pressure control, blood sugar management, reducing processed foods and excess salt, maintaining a healthy weight, and avoiding overuse of medications that stress the kidneys. Dehydration can temporarily lower eGFR by reducing blood flow to the kidneys. Medications like NSAIDs, certain antibiotics, and some blood pressure drugs can affect kidney function when used long term or at high doses.
High blood pressure and diabetes are the leading causes of chronic kidney disease. Both conditions damage the small blood vessels in your kidneys over time. Other factors that affect eGFR include heart disease, urinary tract blockages, autoimmune conditions, severe infections, and a diet high in processed foods and animal protein.
How to Improve Your eGFR
- Drink enough water daily to keep urine pale yellow and support kidney filtration
- Control blood pressure through reduced salt intake, stress management, and regular monitoring
- Manage blood sugar levels with balanced meals and limited refined carbohydrates
- Eat more plant-based foods and limit processed meats and excess animal protein
- Maintain a healthy weight through regular physical activity and portion control
- Avoid overuse of NSAIDs like ibuprofen and naproxen that can stress kidneys
- Limit alcohol consumption to reduce strain on kidney filtration
- Work with your doctor to adjust medications that may affect kidney function
- Get regular sleep of 7 to 9 hours to support overall metabolic health
- Reduce exposure to environmental toxins and heavy metals when possible
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FAQ
eGFR stands for estimated glomerular filtration rate. It measures how well your kidneys filter waste and excess fluid from your blood. The test uses your creatinine level, age, sex, and race to calculate this estimate. It is one of the best indicators of overall kidney health.
A normal eGFR is typically 90 or higher in adults. Values between 60 and 89 may be normal for older adults but should be monitored. Anything below 60 for three months or more indicates chronic kidney disease. Your doctor will interpret your results based on your age and health history.
Low eGFR can be caused by chronic conditions like diabetes and high blood pressure that damage kidneys over time. Acute causes include dehydration, serious infections, certain medications, reduced blood flow to the kidneys, or urinary tract blockages. Heart disease and autoimmune conditions can also reduce kidney function. Early detection allows for lifestyle changes to slow or prevent further decline.
Yes, dehydration can temporarily lower your eGFR by reducing blood flow to your kidneys. This makes it harder for them to filter waste effectively. Drink plenty of water before your test unless your doctor tells you otherwise. If your eGFR is low, your doctor may retest after you are well hydrated to see if it improves.
Protect your kidneys by staying hydrated, controlling blood pressure and blood sugar, reducing salt and processed foods, and maintaining a healthy weight. Limit NSAIDs like ibuprofen and avoid excessive animal protein. Regular exercise, good sleep, and stress management also support kidney health. Work with your doctor to address underlying conditions and adjust any medications that may harm your kidneys.
NSAIDs like ibuprofen and naproxen, certain antibiotics, some blood pressure medications, and contrast dyes used in imaging tests can reduce eGFR. Overuse of these medications can stress your kidneys and cause temporary or permanent damage. Always tell your doctor about all medications and supplements you take. They can help you find safer alternatives if needed.
Yes, eGFR naturally declines slightly as you age due to normal changes in kidney structure and blood flow. Older adults may have an eGFR between 60 and 89 without kidney disease. However, values below 60 still require monitoring and evaluation. Your doctor will consider your age, symptoms, and other test results when interpreting your eGFR.
Creatinine is a waste product from muscle breakdown that your kidneys filter from your blood. eGFR is a calculation based on your creatinine level, age, sex, and race that estimates how well your kidneys are filtering. High creatinine usually means lower eGFR, indicating reduced kidney function. eGFR is considered more accurate for assessing overall kidney health.
In acute kidney injury caused by dehydration, infection, or temporary medication effects, eGFR can improve with treatment. Chronic kidney disease is usually not reversible, but lifestyle changes can slow or stop progression. Early intervention with blood pressure control, blood sugar management, diet changes, and proper hydration can preserve remaining kidney function. Regular monitoring helps catch problems early.
See your doctor if your eGFR is below 60, especially if it has dropped from previous tests. Also seek care if you have symptoms like swelling, fatigue, changes in urination, or unexplained nausea. If you have diabetes, high blood pressure, or heart disease, regular eGFR monitoring is essential. Early detection and treatment can prevent progression to kidney failure.
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