eGFR Calculator
Estimated Glomerular Filtration Rate (eGFR): A Key Indicator of Kidney Health
The Estimated Glomerular Filtration Rate (eGFR) is a crucial measurement used to evaluate how well the kidneys are functioning. It provides an estimate of the rate at which the kidneys filter waste from the blood, which is essential in diagnosing and managing kidney disease. Understanding eGFR can help individuals take better care of their kidney health and seek timely medical advice.
What Is eGFR?
eGFR is a calculated value that estimates the actual glomerular filtration rate (GFR)—the amount of blood filtered by the glomeruli (tiny filters in the kidneys) each minute. Since directly measuring GFR is complex and time-consuming, eGFR is used in everyday clinical practice as a reliable alternative. It is derived from a blood test that measures creatinine, a waste product produced by muscle metabolism.
How Is eGFR Calculated?
The eGFR is calculated using a formula that includes:
- Serum creatinine level
- Age
- Sex
- Race (in some formulas)
One of the most commonly used equations is the CKD-EPI formula. This equation adjusts for differences in muscle mass and other factors that can affect creatinine levels.
Normal eGFR Range
A normal eGFR is typically:
- 90 to 120 mL/min/1.73 m² in healthy individuals.
However, eGFR tends to decline naturally with age. An eGFR below 60 mL/min/1.73 m² for three months or more may indicate chronic kidney disease (CKD).
Stages of Kidney Disease Based on eGFR
| Stage | eGFR (mL/min/1.73 m²) | Kidney Function |
|---|---|---|
| Stage 1 | ≥90 | Normal or high |
| Stage 2 | 60–89 | Mildly decreased |
| Stage 3a | 45–59 | Mild to moderately decreased |
| Stage 3b | 30–44 | Moderately to severely decreased |
| Stage 4 | 15–29 | Severely decreased |
| Stage 5 | <15 | Kidney failure (End-stage renal disease) |
Why Is eGFR Important?
eGFR plays a central role in:
- Detecting early kidney damage
- Monitoring progression of kidney disease
- Guiding treatment decisions
- Evaluating the safety of medications that are cleared by the kidneys
An abnormal eGFR result doesn’t always mean you have kidney disease. Temporary factors like dehydration, certain medications, or a high-protein diet can also influence the result. That’s why doctors may repeat the test or use additional tests for confirmation.
Factors That Can Affect eGFR Accuracy
While eGFR is a valuable tool, several factors may impact its accuracy:
- Muscle mass: People with very low or very high muscle mass may have skewed results.
- Dietary protein intake: High protein diets can temporarily raise creatinine.
- Certain medications: Some drugs can interfere with creatinine levels.
- Ethnicity: Some formulas include race, but newer approaches aim to move away from race-based calculations.
Improving or Maintaining a Healthy eGFR
To support healthy kidney function and maintain a normal eGFR:
- Stay hydrated
- Manage blood pressure and blood sugar
- Avoid excessive use of NSAIDs and other nephrotoxic drugs
- Follow a kidney-friendly diet if recommended
- Get regular checkups, especially if you’re at risk (e.g., diabetes, hypertension, family history of kidney disease)
Conclusion
The Estimated Glomerular Filtration Rate (eGFR) is a powerful yet simple tool for assessing kidney function. Regular monitoring of eGFR can help detect kidney problems early and guide effective treatment. By understanding what eGFR means and how to maintain healthy levels, individuals can take proactive steps toward preserving their kidney health and overall well-being.