Estimated Glomerular Filtration Rate (eGFR)
Understanding eGFR
The estimated Glomerular Filtration Rate (eGFR) is a key measure of kidney function. It estimates how well your kidneys filter blood and is used to diagnose and monitor chronic kidney disease (CKD). This calculator uses the 2021 CKD-EPI creatinine-cystatin C equation, which provides accurate estimates for adult patients without using race in the calculation.
What is eGFR?
eGFR measures how many milliliters of blood your kidneys can filter per minute, adjusted for body surface area. It's calculated using your serum creatinine level, age, and sex. For increased accuracy, cystatin C is recommended when available, as it provides more accurate results and eliminates potential disparities between different populations.
Normal eGFR Values and CKD Categories
| Category | eGFR (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | ≥90 | Normal or high |
| G2 | 60-89 | Mildly decreased |
| G3a | 45-59 | Mild to moderately decreased |
| G3b | 30-44 | Moderately to severely decreased |
| G4 | 15-29 | Severely decreased |
| G5 | <15 | Kidney failure |
Clinical Significance
Low eGFR
May indicate:
- Chronic kidney disease
- Acute kidney injury
- Reduced kidney function
- Need for closer monitoring
Normal eGFR
Indicates:
- Healthy kidney function
- Adequate filtration
- No immediate kidney concerns
Important Considerations
- Results should be interpreted by a healthcare professional
- Multiple measurements over time are more valuable than a single result
- Other kidney function tests may be needed for complete assessment
- Factors like dehydration can temporarily affect results
- When available, using both creatinine and cystatin C provides the most accurate results
- This calculator uses the latest race-free equation for more equitable assessment
When to Seek Medical Attention
Consult a healthcare provider if:
- eGFR is below 60 mL/min/1.73m²
- eGFR is declining over time
- You have symptoms of kidney problems
- You have risk factors for kidney disease
Limitations
This calculator:
- Is for adults 18 years and older
- May be less accurate in certain populations
- Should not replace clinical judgment
- Requires accurate input values
Tips for Accurate Results
- Use recent laboratory values
- Ensure correct units
- Consider multiple measurements
- Account for temporary factors
Factors Affecting eGFR
Creatinine levels can be affected by
- Muscle mass
- Diet
- Exercise
- Medications
- Hydration status
Cystatin C levels can be affected by
- Thyroid function
- Inflammation
- Obesity
- Smoking status
- Certain medications
Clinical Applications
eGFR is particularly useful for:
- Diagnosing CKD
- Monitoring kidney function
- Adjusting medication doses
- Planning treatment strategies
- Assessing kidney disease progression
Calculate your eGFR now to better understand your kidney function!
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