The Glomerular Filtration Rate (GFR) is a key indicator of kidney function. It measures how much blood your kidneys filter per minute. A lower GFR can indicate kidney disease. This calculator uses the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) 2009 equation, which is widely accepted for estimating GFR based on serum creatinine, age, sex, and race.
Estimated GFR:
Enter values and click 'Calculate GFR'.
Understanding Your GFR Result
GFR is expressed in milliliters per minute per 1.73 square meters (mL/min/1.73 m²), which is a standard body surface area. Here's a general guide to what your GFR might mean:
90 or higher: Normal kidney function.
60-89: Mildly decreased kidney function. Often, no symptoms are present, but monitoring is recommended.
45-59: Mild to moderate decrease in kidney function. This indicates Stage 3a Chronic Kidney Disease (CKD).
30-44: Moderate to severe decrease in kidney function. This indicates Stage 3b CKD.
15-29: Severely decreased kidney function. This indicates Stage 4 CKD.
Less than 15: Kidney failure. This indicates Stage 5 CKD, often requiring dialysis or kidney transplant.
It's important to remember that GFR is an estimate, and other factors like acute kidney injury, certain medications, or extreme body sizes can affect its accuracy. Always consult with a healthcare professional to interpret your GFR results and discuss your kidney health.
Why is GFR Important?
Monitoring GFR helps in the early detection and management of kidney disease. Early intervention can slow the progression of kidney damage and prevent serious complications. Regular GFR checks are especially important for individuals with risk factors such as diabetes, high blood pressure, heart disease, or a family history of kidney failure.
Examples:
Example 1: A 45-year-old Non-African American Male with a Serum Creatinine of 1.0 mg/dL would have an estimated GFR of approximately 94 mL/min/1.73 m². This is considered normal kidney function.
Example 2: A 60-year-old African American Female with a Serum Creatinine of 1.5 mg/dL would have an estimated GFR of approximately 42 mL/min/1.73 m². This indicates moderate to severe kidney function decrease (Stage 3b CKD).
Example 3: A 70-year-old Non-African American Male with a Serum Creatinine of 0.8 mg/dL would have an estimated GFR of approximately 85 mL/min/1.73 m². This is mildly decreased kidney function.
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function calculateGFR() {
var serumCreatinine = parseFloat(document.getElementById('serumCreatinine').value);
var age = parseInt(document.getElementById('age').value);
var sex = document.querySelector('input[name="sex"]:checked').value;
var race = document.querySelector('input[name="race"]:checked').value;
if (isNaN(serumCreatinine) || serumCreatinine <= 0) {
document.getElementById('gfrResult').innerHTML = 'Please enter a valid positive Serum Creatinine value.';
return;
}
if (isNaN(age) || age 120) {
document.getElementById('gfrResult').innerHTML = 'Please enter a valid Age (18-120 years).';
return;
}
var gfr;
var kappa; // 0.7 for female, 0.9 for male
var alpha; // exponent based on creatinine and sex
var raceFactor = 1;
if (sex === 'female') {
kappa = 0.7;
if (serumCreatinine <= kappa) {
alpha = -0.329;
} else {
alpha = -1.209;
}
gfr = 144 * Math.pow(serumCreatinine / kappa, alpha) * Math.pow(0.993, age);
} else { // male
kappa = 0.9;
if (serumCreatinine <= kappa) {
alpha = -0.411;
} else {
alpha = -1.209;
}
gfr = 141 * Math.pow(serumCreatinine / kappa, alpha) * Math.pow(0.993, age);
}
if (race === 'africanAmerican') {
raceFactor = 1.159;
}
gfr *= raceFactor;
document.getElementById('gfrResult').innerHTML = 'Estimated GFR: ' + gfr.toFixed(2) + ' mL/min/1.73 m²';
}