Calculate Estimated Glomerular Filtration Rate

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Estimated Glomerular Filtration Rate (eGFR) Calculator

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.calculator-container { font-family: sans-serif; border: 1px solid #ccc; padding: 20px; border-radius: 8px; max-width: 500px; margin: 20px auto; } .calculator-inputs { margin-bottom: 20px; } .input-group { margin-bottom: 15px; } .input-group label { display: block; margin-bottom: 5px; font-weight: bold; } .input-group input, .input-group select { width: 100%; padding: 8px; border: 1px solid #ccc; border-radius: 4px; box-sizing: border-box; /* Ensures padding doesn't affect width */ } button { background-color: #4CAF50; color: white; padding: 10px 15px; border: none; border-radius: 4px; cursor: pointer; font-size: 16px; } button:hover { background-color: #45a049; } .calculator-result { margin-top: 20px; font-size: 1.1em; font-weight: bold; color: #333; } 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 egfr = 0; // Check if inputs are valid numbers if (isNaN(serumCreatinine) || isNaN(age) || serumCreatinine <= 0 || age <= 0) { document.getElementById("result").innerText = "Please enter valid positive numbers for Serum Creatinine and Age."; return; } // CKD-EPI 2009 Equation (common and widely used) // Factors for CKD-EPI 2009 var a = -0.302; // for females and non-black males var b = -0.241; // for black females var c = 1.012; // for black males var raceFactor = 1; if (race === "african_american") { if (gender === "male") { raceFactor = c; } else { // black female raceFactor = b; } } else { // other or female raceFactor = a; } // Calculate eGFR egfr = 186 * Math.pow(serumCreatinine, -1.154) * Math.pow(age, -0.203); if (gender === "female" && race !== "african_american") { egfr = egfr * Math.exp(a * Math.log(serumCreatinine / 0.7)); // Simplified for female/non-black } else if (gender === "male" && race !== "african_american") { egfr = egfr * Math.exp(a * Math.log(serumCreatinine / 1.2)); // Simplified for male/non-black } else if (gender === "female" && race === "african_american") { egfr = egfr * Math.exp(b * Math.log(serumCreatinine / 0.7)); // Simplified for black female } else if (gender === "male" && race === "african_american") { egfr = egfr * Math.exp(raceFactor * Math.log(serumCreatinine / 1.2)); // Simplified for black male } // Ensure eGFR is not negative if (egfr < 0) { egfr = 0; } // Round to nearest whole number for display egfr = Math.round(egfr); var resultText = "Estimated GFR: " + egfr + " mL/min/1.73 m²"; document.getElementById("result").innerText = resultText; }

Understanding Estimated Glomerular Filtration Rate (eGFR)

The Estimated Glomerular Filtration Rate (eGFR) is a crucial blood test that indicates how well your kidneys are functioning. It measures the amount of blood your kidneys filter per minute. A healthy kidney function is vital for removing waste products and excess fluid from your body.

Why is eGFR Important?

Kidney disease often progresses silently, especially in its early stages. An eGFR test helps healthcare providers detect potential kidney problems early, allowing for timely intervention and management. This can slow down or prevent further damage to the kidneys and reduce the risk of complications like heart disease.

How is eGFR Calculated?

The eGFR is not directly measured but is estimated using formulas that take into account your serum creatinine level, age, sex, and race. The most commonly used formula is the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation.

  • Serum Creatinine: This is a waste product generated from muscle metabolism. Healthy kidneys filter creatinine out of the blood. If your kidneys are not functioning well, creatinine levels in your blood will rise.
  • Age: Kidney function naturally declines slightly with age.
  • Sex: Men and women can have different muscle mass and therefore slightly different creatinine levels.
  • Race: Historically, race has been included in eGFR calculations due to observed differences in creatinine levels, though its inclusion is a subject of ongoing discussion and refinement in medical practice.

Interpreting Your eGFR Results

eGFR values are reported in milliliters per minute per 1.73 square meters of body surface area (mL/min/1.73 m²). Generally, higher eGFR values indicate better kidney function.

  • eGFR of 90 or higher: Usually considered normal.
  • eGFR below 60 for three months or more: This can indicate chronic kidney disease (CKD).
  • eGFR below 15: This may indicate kidney failure, requiring immediate medical attention and likely kidney replacement therapy (dialysis or transplant).

It's important to discuss your eGFR results with your doctor. They will interpret the results in the context of your overall health, medical history, and other test results.

Factors Affecting eGFR

Several factors can influence your serum creatinine levels and, consequently, your eGFR. These include:

  • Muscle mass (higher muscle mass can lead to higher creatinine)
  • Diet (e.g., high protein intake)
  • Certain medications
  • Vigorous exercise

This calculator provides an *estimated* eGFR. It is a tool for informational purposes and should not replace professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.

Example Calculation:

Let's consider a 65-year-old male who identifies as African American and has a serum creatinine level of 1.3 mg/dL.

Using the CKD-EPI equation, with the appropriate adjustments for sex, age, and race, his estimated eGFR might be calculated. For instance, after inputting these values into the calculator, the output could show an eGFR of approximately 55 mL/min/1.73 m². This result would suggest a potential stage 3 chronic kidney disease, warranting further medical evaluation.

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