Key Takeaways
- eGFR measures how well your kidneys filter waste from blood
- Normal eGFR is 90 mL/min or higher
- eGFR below 60 for 3+ months indicates chronic kidney disease
- Early detection can slow or prevent kidney disease progression
- Creatinine, age, and gender are key factors in eGFR calculation
What Is eGFR (Estimated Glomerular Filtration Rate)?
Estimated Glomerular Filtration Rate (eGFR) is a measure of how well your kidneys filter waste products from your blood. It estimates the amount of blood that passes through the glomeruli (tiny filters in the kidneys) each minute. eGFR is the most reliable indicator of kidney function and is used to diagnose and monitor chronic kidney disease (CKD).
The glomeruli are microscopic blood vessel clusters in the kidneys that filter blood. As kidney function declines, less blood gets filtered, leading to waste buildup in the body. Regular eGFR testing helps detect kidney problems early, when treatment is most effective.
How Is eGFR Calculated?
This calculator uses the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation, which considers:
- Serum Creatinine: A waste product from muscle metabolism filtered by the kidneys
- Age: Kidney function naturally declines with age
- Gender: Males typically have higher creatinine levels due to greater muscle mass
Understanding Kidney Disease Stages
Based on your eGFR, kidney function is classified into five stages:
| Stage | eGFR (mL/min) | Kidney Function | Description |
|---|---|---|---|
| Stage 1 | 90 or higher | Normal | Kidneys work normally; may have other signs of damage |
| Stage 2 | 60-89 | Mildly Reduced | Mild kidney damage with slight decrease in function |
| Stage 3a | 45-59 | Mild-Moderate | Moderate damage; may need lifestyle changes |
| Stage 3b | 30-44 | Moderate-Severe | Moderate damage; closer monitoring needed |
| Stage 4 | 15-29 | Severely Reduced | Severe damage; prepare for kidney failure treatment |
| Stage 5 | Below 15 | Kidney Failure | Kidneys have failed; dialysis or transplant needed |
Important Medical Disclaimer
This calculator provides an estimate only and should not replace professional medical advice. If your eGFR is below 60 or you have concerns about your kidney health, please consult a healthcare provider immediately. Only a doctor can properly diagnose kidney disease through comprehensive testing.
What Affects Creatinine and eGFR Levels?
Factors That Can Raise Creatinine (Lower eGFR)
- Dehydration or insufficient fluid intake
- High-protein diet or creatine supplements
- Intense exercise or strenuous physical activity
- Certain medications (NSAIDs, some antibiotics)
- Kidney disease or damage
- Diabetes and high blood pressure
Factors That Can Lower Creatinine (Raise eGFR)
- Low muscle mass or muscle wasting diseases
- Malnutrition or severe weight loss
- Pregnancy (increased blood volume)
- Some liver diseases
Pro Tip: Protecting Your Kidney Health
The best ways to maintain healthy kidneys include: staying hydrated, controlling blood pressure, managing diabetes, avoiding excessive NSAIDs, limiting salt intake, exercising regularly, and getting annual checkups including kidney function tests.
When Should You Get Your eGFR Tested?
Regular kidney function testing is recommended for people at higher risk:
- Those with diabetes - should be tested annually
- Those with high blood pressure - annual testing recommended
- People with family history of kidney disease
- Those over age 60 - regular screening advised
- People with heart disease or who have had a heart attack
- Those who are obese or have metabolic syndrome
Frequently Asked Questions
An eGFR below 15 mL/min indicates kidney failure (Stage 5 CKD) and is considered dangerous. At this level, dialysis or kidney transplant is typically needed. However, any eGFR consistently below 60 warrants medical attention and monitoring.
Yes, in some cases eGFR can improve. Lifestyle changes like controlling blood pressure, managing diabetes, staying hydrated, eating a kidney-friendly diet, exercising, and avoiding nephrotoxic medications can help. Early-stage kidney disease is often reversible with proper treatment.
For healthy adults, annual testing is sufficient. Those with diabetes, hypertension, or CKD may need testing every 3-6 months. Your doctor will recommend the appropriate frequency based on your risk factors and current kidney function.
Early kidney disease often has no symptoms. Later signs include fatigue, swelling in ankles/feet, frequent urination (especially at night), foamy urine, persistent itching, loss of appetite, muscle cramps, and difficulty concentrating. Don't wait for symptoms - get regular testing if you're at risk.
Yes, kidney function naturally declines with age. eGFR decreases by approximately 1 mL/min per year after age 30. A healthy 80-year-old may have an eGFR of 60-70, which could be normal for their age. Your doctor interprets results considering your age and overall health.