Black or African American
Not Black or African American
Understanding the eGFR Calculator and Kidney Function
The Estimated Glomerular Filtration Rate (eGFR) is a crucial indicator of kidney function. It measures how well your kidneys are filtering waste products and excess fluid from your blood. A lower eGFR suggests that your kidneys are not working as well as they should be. This calculator uses commonly accepted formulas to estimate your GFR based on standard laboratory values.
Why is eGFR Important?
Kidney disease often progresses silently, meaning you might not experience symptoms until the disease is advanced. Regular eGFR testing is essential for:
Detecting kidney disease early.
Monitoring the progression of kidney disease.
Adjusting medication dosages, as kidneys play a role in drug metabolism and excretion.
Identifying individuals at risk for chronic kidney disease (CKD) and its complications, such as heart disease, anemia, and bone disease.
The MDRD and CKD-EPI Formulas
The most widely used formulas for calculating eGFR are the Modification of Diet in Renal Disease (MDRD) Study equation and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The CKD-EPI 2021 equation is considered more accurate and is increasingly adopted by laboratories worldwide. This calculator primarily uses the CKD-EPI 2021 formula.
CKD-EPI 2021 Formula (Simplified Representation for Calculation Logic)
The CKD-EPI 2021 equation is complex and involves several steps and specific parameters.
For males:
If serum creatinine <= 0.9 and race is Black: eGFR = 135 * (serum creatinine / 0.9)^(-0.971) * (age)^(-0.171)
If serum creatinine 0.9 and race is Black: eGFR = 135 * (serum creatinine / 0.9)^(-1.079) * (age)^(-0.171) * 0.996^(number of additional years over 40)
If serum creatinine > 0.9 and race is Not Black: eGFR = 141 * (serum creatinine / 0.9)^(-1.079) * (age)^(-0.171) * 0.996^(number of additional years over 40)
For females:
If serum creatinine <= 0.7 and race is Black: eGFR = 166 * (serum creatinine / 0.7)^(-0.971) * (age)^(-0.171) * 1.012
If serum creatinine 0.7 and race is Black: eGFR = 166 * (serum creatinine / 0.7)^(-1.133) * (age)^(-0.171) * 0.996^(number of additional years over 40) * 1.012
If serum creatinine > 0.7 and race is Not Black: eGFR = 141 * (serum creatinine / 0.7)^(-1.133) * (age)^(-0.171) * 0.996^(number of additional years over 40) * 1.012
Note: The 'race' factor for Black individuals is an adjustment applied by the original CKD-EPI formula. The 2021 update removed the race factor from the main equation, but for compatibility and common usage, some calculators may still incorporate it or use the updated version. For simplicity in this calculator's *displayed* formula, we present a generalized form, but the code implements a version reflecting clinical usage. The most current guidelines often recommend using a race-free equation.
The calculator below uses a simplified implementation reflecting the CKD-EPI 2021 approach without race adjustment for broader applicability and alignment with evolving medical standards.
Interpreting the Results
The result is your estimated GFR in milliliters per minute per 1.73 square meters (mL/min/1.73 m²).
eGFR ≥ 90 mL/min/1.73 m²: Usually considered normal kidney function, but other factors should be considered.
eGFR 60-89 mL/min/1.73 m²: Mildly decreased kidney function. Check for other signs of kidney damage (e.g., protein in urine).
Disclaimer: This calculator is for informational purposes only and does not substitute professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment related to kidney health.
function calculateeGFR() {
var serumCreatinine = parseFloat(document.getElementById("serumCreatinine").value);
var age = parseInt(document.getElementById("age").value);
var gender = document.getElementById("gender").value;
var race = document.getElementById("race").value;
var resultDiv = document.getElementById("result");
resultDiv.style.display = 'block';
if (isNaN(serumCreatinine) || isNaN(age) || serumCreatinine <= 0 || age <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for Serum Creatinine and Age.";
resultDiv.style.backgroundColor = "#dc3545"; // Error color
resultDiv.style.animation = "none";
return;
}
var egfr;
var isBlack = (race === "black");
var isMale = (gender === "male");
// CKD-EPI 2021 Formula (simplified, race-agnostic version for broader applicability)
// Ref: https://www.kidney.org/professionals/gfr_calculator_2021
// This calculator uses the simplified approach, aligning with current trends away from race adjustment.
// The original CKD-EPI had race coefficients. The 2021 update and subsequent guidelines often advocate for race-free calculation.
var Cr; // Corrected creatinine value
var A = age; // Age
var Sf = 1; // Sex factor
var k = 0.7; // Constant based on sex and race (simplified)
if (isMale) {
Sf = 1.018;
k = 0.975;
} else {
Sf = 1; // Female
k = 0.703;
}
Cr = serumCreatinine / k;
if (Cr < 0) Cr = 0; // Ensure Cr is not negative
if (Cr <= 1) {
egfr = 141 * Math.pow(Cr, -0.329) * Math.pow(0.993, A) * Sf;
} else {
egfr = 121.5 * Math.pow(Cr, -1.209) * Math.pow(0.993, A) * Sf;
}
// Round to nearest whole number
egfr = Math.round(egfr);
// Ensure eGFR is not negative
if (egfr < 0) egfr = 0;
resultDiv.innerHTML = egfr + " mL/min/1.73 m²" + "Estimated Glomerular Filtration Rate";
resultDiv.style.backgroundColor = "var(–success-green)"; // Reset to success color
resultDiv.style.animation = "pulse 1.5s infinite";
}