Understanding Your GFR
The Glomerular Filtration Rate (GFR) is a crucial measurement of kidney health. It represents the volume of fluid that is filtered from the glomerular capillaries into Bowman's capsule per unit of time. A normal GFR typically ranges from 90 mL/min/1.73 m² or higher.
Interpreting GFR Values:
- GFR ≥ 90 mL/min/1.73 m²: Kidneys are functioning normally or with mild impairment.
- GFR 60-89 mL/min/1.73 m²: Mild decrease in kidney function.
- GFR 30-59 mL/min/1.73 m²: Moderate decrease in kidney function.
- GFR 15-29 mL/min/1.73 m²: Severe decrease in kidney function.
- GFR < 15 mL/min/1.73 m²: Kidney failure.
Important Note: This calculator provides an estimate based on the CKD-EPI equation. It is not a substitute for professional medical advice. Always consult with your healthcare provider for accurate diagnosis and treatment.
function calculateGFR() {
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 gfrValueElement = document.getElementById("gfrValue");
var gfrInterpretationElement = document.getElementById("gfrInterpretation");
if (isNaN(serumCreatinine) || isNaN(age) || serumCreatinine <= 0 || age = 18 years
// For men: GFR = 142 x (sCr/0.9) ^ -0.329 x 0.9938 ^ age x 1.012 (if Black)
// For women: GFR = 142 x (sCr/0.7) ^ -0.329 x 0.9938 ^ age x 1.012 (if Black)
var scrForCalc = serumCreatinine;
if (gender === "female") {
scrForCalc = serumCreatinine / 0.7;
} else { // male
scrForCalc = serumCreatinine / 0.9;
}
gfr = 142 * Math.pow(scrForCalc, -0.329) * Math.pow(0.9938, age) * Math.pow(1.012, (race === "black" ? 1 : 0));
// Adjust for women if needed by a separate factor. This is simplified for this example.
// The 2021 CKD-EPI equation has nuances with gender and race interaction,
// but a simplified application is presented here for clarity.
if (gender === "female" && race === "non-black") {
// For women, the initial SCr adjustment is different.
// The equation used above already incorporates a base for female by adjusting SCr by 0.7.
// The race factor adjustment is applied universally.
// A specific multiplicative factor for females is sometimes applied, but the 2021 equation
// primarily adjusts the SCr threshold and the base constant for females.
// The formula provided in many sources for CKD-EPI 2021 for females is:
// GFR = 142 x (sCr/0.7) ^ -0.329 x 0.9938 ^ age x 1.012 (if Black)
// This means the above calculation *should* be correct for females as well, with the SCr adjustment.
}
if (gfr = 90) {
interpretation = "Normal or mild decrease in kidney function.";
} else if (gfr >= 60) {
interpretation = "Mild decrease in kidney function.";
} else if (gfr >= 30) {
interpretation = "Moderate decrease in kidney function.";
} else if (gfr >= 15) {
interpretation = "Severe decrease in kidney function.";
} else {
interpretation = "Kidney failure.";
}
gfrValueElement.textContent = gfr.toFixed(2) + " mL/min/1.73 m²";
gfrInterpretationElement.textContent = "Interpretation: " + interpretation;
}
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font-family: sans-serif;
max-width: 700px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
background-color: #f9f9f9;
}
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margin-bottom: 20px;
padding: 15px;
border: 1px solid #eee;
border-radius: 5px;
background-color: #fff;
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text-align: center;
color: #333;
margin-bottom: 15px;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
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.form-group select {
width: calc(100% – 12px);
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box; /* Include padding and border in the element's total width and height */
}
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width: 100%;
padding: 10px;
background-color: #007bff;
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font-size: 16px;
cursor: pointer;
transition: background-color 0.3s ease;
}
.calculator-form button:hover {
background-color: #0056b3;
}
.calculator-result {
padding: 15px;
border: 1px solid #eee;
border-radius: 5px;
background-color: #fff;
text-align: center;
}
.calculator-result h3 {
margin-top: 0;
color: #333;
}
#gfrValue {
font-size: 1.8em;
font-weight: bold;
color: #007bff;
margin-bottom: 5px;
}
#gfrInterpretation {
font-style: italic;
color: #666;
}
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padding: 15px;
border: 1px solid #eee;
border-radius: 5px;
background-color: #fff;
}
.calculator-explanation h3,
.calculator-explanation h4 {
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margin-bottom: 10px;
}
.calculator-explanation ul {
list-style-type: disc;
margin-left: 20px;
}
.calculator-explanation li {
margin-bottom: 8px;
}
.calculator-explanation p {
line-height: 1.6;
color: #444;
}