Why is Estimated GFR (eGFR) Low? Causes, Symptoms, and What to Do

Estimated Glomerular Filtration Rate (eGFR) is a key indicator of how well your kidneys are filtering waste from your blood. A low eGFR can be a sign of kidney disease or other health issues. Understanding why your eGFR is low and what it means for your health can help you and your healthcare provider make informed decisions.

What is eGFR and Why is it Important?

The eGFR is an estimate of the rate at which your kidneys filter blood. It is calculated based on your blood creatinine level, age, sex, and sometimes race. Creatinine is a waste product from muscle activity that is filtered out by the kidneys. The eGFR is measured in milliliters per minute per 1.73 meters squared (mL/min/1.73 m²). A normal eGFR is typically above 90 mL/min/1.73 m², indicating healthy kidney function. The eGFR is important because it helps detect kidney disease early, even before symptoms appear.

Causes of Low eGFR

A low eGFR can be caused by various factors, including:

• Chronic Kidney Disease (CKD): This is a long-term condition where the kidneys do not work as well as they should. It's the most common cause of a low eGFR.
• Acute Kidney Injury (AKI): A sudden decrease in kidney function due to injury, infection, or severe dehydration can lower eGFR.
• High Blood Pressure and Diabetes: Both conditions can damage the kidneys over time, leading to a lower eGFR.
• Age: Kidney function naturally declines with age, which may result in a lower eGFR.
• Certain Medications: Some drugs can affect kidney function, leading to a temporary or permanent decrease in eGFR.

Symptoms of Low eGFR

A low eGFR might not cause symptoms initially. However, as kidney function declines, you may experience:

• Fatigue: Feeling more tired than usual.
• Swelling: Especially in the legs, ankles, or feet due to fluid retention.
• Changes in Urination: Such as foamy urine or urinating less often.
• Shortness of Breath: Caused by fluid buildup in the lungs.
• Confusion or Difficulty Concentrating: Due to toxin buildup in the blood.

How to Interpret Your eGFR Results

Understanding your eGFR results can help you and your doctor monitor your kidney health:

• Normal eGFR (90 mL/min/1.73 m² or above): Indicates healthy kidney function.
• Mildly Decreased eGFR (60-89 mL/min/1.73 m²): May indicate early-stage kidney disease, especially if other signs of kidney damage are present.
• Moderately Decreased eGFR (30-59 mL/min/1.73 m²): Suggests more significant kidney impairment.
• Severely Decreased eGFR (15-29 mL/min/1.73 m²): Indicates severe kidney damage.
• Kidney Failure (eGFR less than 15 mL/min/1.73 m²): The kidneys are close to failing or have failed.

Managing a Low eGFR

If your eGFR is low, there are steps you can take:

• Follow Your Doctor's Advice: They may recommend lifestyle changes, medications, or further testing.
• Manage Underlying Conditions: Control blood pressure and diabetes if applicable.
• Healthy Diet: A diet low in sodium, potassium, and phosphorus can help manage kidney health.
• Stay Hydrated: Drink enough water to stay hydrated, but consult your doctor about the right amount for you.
• Regular Monitoring: Keep up with regular check-ups to monitor your kidney function.

Frequently Asked Questions

What does a low eGFR mean? A low eGFR indicates that your kidneys are not filtering blood as well as they should, which could be a sign of kidney disease or other health issues.

Can eGFR improve? In some cases, eGFR can improve with treatment of underlying conditions, lifestyle changes, or medication adjustments.

Does a low eGFR always mean kidney disease? Not always. It can also result from temporary factors like dehydration or certain medications.

How often should eGFR be tested? This depends on your health status and doctor's recommendations, but regular monitoring is crucial if you have risk factors for kidney disease.

When to See a Doctor

If you have a low eGFR, it's important to discuss the results with your doctor. Seek medical advice if you experience symptoms like persistent fatigue, swelling, or changes in urination. Early detection and management are key to maintaining kidney health.

This information is for educational purposes only and should not replace professional medical advice. Always consult with a healthcare provider for decisions about your health.