eGFR (Estimated Glomerular Filtration Rate – Calculation)

The eGFR (Estimated Glomerular Filtration Rate) test is a calculated value used to assess how well the kidneys are filtering blood. It estimates kidney function based on serum creatinine levels, age, sex, and sometimes race. eGFR is a key tool in diagnosing and monitoring chronic kidney disease (CKD).

1. What Is eGFR?

• eGFR estimates the rate at which the kidneys filter waste products from the blood (measured in mL/min/1.73 m²).

• It is calculated using mathematical formulas such as the CKD-EPI or MDRD equations.

• The most commonly used variables include serum creatinine, age, sex, and sometimes race.

2. Why Is the eGFR Test Performed?

This test is used to:

• Assess overall kidney function.

• Detect early signs of chronic kidney disease (CKD).

• Monitor progression of CKD or kidney damage over time.

• Guide treatment decisions for patients with diabetes, hypertension, or kidney disease.

3. eGFR Reference Ranges and Stages of CKD

• Normal: ≥ 90 mL/min/1.73 m²

• Mild decrease: 60 – 89 mL/min/1.73 m²

• Moderate decrease: 30 – 59 mL/min/1.73 m² (CKD Stage 3)

• Severe decrease: 15 – 29 mL/min/1.73 m² (CKD Stage 4)

• Kidney failure: < 15 mL/min/1.73 m² (CKD Stage 5 – may require dialysis)

4. How to Interpret eGFR Results

🔹 eGFR ≥ 90:

• Normal kidney function if no other markers of damage are present.

🔹 eGFR 60–89:

• Mildly reduced function—monitor if other risk factors (e.g., diabetes, proteinuria) are present.

🔹 eGFR < 60:

• Indicates chronic kidney disease. Requires closer monitoring and potential intervention.

5. What Can Affect eGFR Results?

• Muscle mass (high in muscular individuals, low in elderly or malnourished)

• Certain medications (e.g., ACE inhibitors, NSAIDs)

• Hydration status and recent protein intake

• Acute illness or infections

• Incorrect blood sampling or lab error

6. How Is the eGFR Calculated?

• eGFR is not directly measured but calculated from serum creatinine using established formulas.

• No special preparation is usually needed; a standard blood draw for creatinine suffices.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have a consistently low eGFR (< 60) across multiple tests.

• Experience symptoms of kidney disease (e.g., fatigue, swelling, foamy urine).

• Have diabetes, hypertension, or a family history of kidney disease.

🔹 Key Takeaways

✅ eGFR is a critical marker of kidney function calculated from creatinine and other factors.

✅ Values < 60 mL/min/1.73 m² may indicate chronic kidney disease.

✅ Monitoring eGFR regularly helps detect kidney issues early and guide management.