MulticalcGFR Calculator
Glomerular Filtration Rate (CKD-EPI Equation)Enter your clinical details to estimate your kidney function and determine your CKD stage.
Your Results
Enter your creatinine and age to see your estimated GFR and kidney health stage.
Understanding GFR and Kidney Health
What is GFR?
Glomerular Filtration Rate (GFR) is the best overall index of kidney function. It measures how much blood passes through the glomeruli—the tiny filters in the kidneys that filter waste from the blood—each minute. Because it is difficult to measure GFR directly, clinicians use "estimated GFR" (eGFR) based on blood tests.
The most common blood test used is Serum Creatinine. Creatinine is a waste product that comes from the normal wear and tear on muscles of the body. When kidneys are functioning well, they filter creatinine out of the blood. As kidney function declines, creatinine levels in the blood rise.
The CKD-EPI Equation
Our calculator uses the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation. This formula is currently considered the most accurate for estimating GFR in adults. It takes into account:
- Serum Creatinine: The primary marker of waste in the blood.
- Age: Kidney function naturally declines as we get older.
- Gender: Men typically have more muscle mass and higher creatinine levels than women.
- Race: Historically, a correction factor was used for Black individuals, though many medical organizations are now moving toward race-neutral equations to ensure equity in care.
Stages of Chronic Kidney Disease (CKD)
Kidney disease is staged based on the GFR value. Understanding these stages helps in managing health and preventing further damage:
| Stage | GFR Range | Description |
|---|---|---|
| Stage 1 | 90+ | Normal or high function; kidney damage may be present (e.g., protein in urine). |
| Stage 2 | 60-89 | Mildly decreased function. |
| Stage 3a | 45-59 | Mildly to moderately decreased function. |
| Stage 3b | 30-44 | Moderately to severely decreased function. |
| Stage 4 | 15-29 | Severely decreased function. |
| Stage 5 | < 15 | Kidney failure (End-Stage Renal Disease). |
Why Kidney Health Matters
Your kidneys perform several vital functions beyond just filtering waste. They regulate blood pressure, produce hormones that make red blood cells, and keep your bones strong by managing calcium and phosphorus levels. Chronic Kidney Disease often has no symptoms in the early stages, which is why regular screening via GFR is so important, especially for those with high blood pressure or diabetes.
Tips for Maintaining Healthy Kidneys
- Control Blood Pressure: High blood pressure is a leading cause of kidney failure.
- Manage Blood Sugar: Diabetes is the #1 cause of kidney disease.
- Stay Hydrated: Water helps the kidneys clear sodium and toxins from the blood.
- Eat a Balanced Diet: Reduce salt intake and processed foods.
- Exercise Regularly: Helps maintain a healthy weight and blood pressure.
- Avoid Overuse of NSAIDs: Common painkillers like ibuprofen can damage kidneys if taken too often.
Frequently Asked Questions
Quick Tips
- Know your creatinine number.
- Stay hydrated before blood tests.
- Limit salt to under 2,300mg/day.
- Monitor your blood pressure daily.
- Consult a nephrologist if GFR < 60.
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Medical Disclaimer
This GFR Calculator is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. eGFR results can be influenced by many factors including muscle mass, diet, and acute illness. Always discuss your results with a qualified healthcare provider. Never ignore professional medical advice or delay seeking it because of something you have read on this website.