CKD-EPI GFR Calculator
Understanding GFR and the CKD-EPI Formula
The Glomerular Filtration Rate (GFR) is a crucial measure of kidney function. It estimates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. A healthy GFR indicates that your kidneys are effectively filtering waste products from your blood.
Chronic Kidney Disease (CKD) is staged based on GFR levels. Early detection and management are vital to slow its progression. The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation is widely recommended for estimating GFR because it is more accurate than older formulas, especially at higher GFRs, and has been validated across diverse populations.
How the CKD-EPI Formula Works
The CKD-EPI 2009 formula uses several key inputs to provide an estimated GFR (eGFR) in mL/min/1.73 m²:
- Serum Creatinine (Scr): A waste product from muscle metabolism. Higher levels can indicate reduced kidney function.
- Age: Kidney function naturally declines with age.
- Sex: Biological sex influences muscle mass and creatinine production.
- Race: The formula includes a race coefficient (for Black individuals) to account for differences in creatinine generation and non-creatinine chromogens, which can affect creatinine measurements.
Interpreting Your GFR Result
GFR values are typically categorized as follows:
- GFR ≥ 90: Normal kidney function
- GFR 60-89: Mildly decreased kidney function (often with other signs of kidney damage for CKD diagnosis)
- GFR 45-59: Mild to moderate decrease in kidney function (CKD Stage 3a)
- GFR 30-44: Moderate to severe decrease in kidney function (CKD Stage 3b)
- GFR 15-29: Severely decreased kidney function (CKD Stage 4)
- GFR < 15: Kidney failure (CKD Stage 5)
Important Note: This calculator provides an estimate based on the CKD-EPI 2009 formula. It is for informational purposes only and should not be used as a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment of any medical condition.
Examples:
Example 1: Female, Non-Black, Age 60, Scr 0.8 mg/dL
Inputting these values into the calculator yields an estimated GFR of approximately 81.8 mL/min/1.73 m². This suggests mildly decreased kidney function, which might be normal for her age or warrant further investigation depending on other clinical factors.
Example 2: Male, Black, Age 45, Scr 1.2 mg/dL
With these inputs, the calculator would show an estimated GFR of approximately 85.9 mL/min/1.73 m². This also falls into the range of mildly decreased kidney function, which a doctor would evaluate in the context of the patient's overall health.