How is Egfr Calculated

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eGFR Calculator (CKD-EPI 2021)

Calculate Estimated Glomerular Filtration Rate for Kidney Function

Male Female
Your Estimated GFR is:
—
mL/min/1.73 m²

How is eGFR Calculated?

The Estimated Glomerular Filtration Rate (eGFR) is the standard test used by healthcare professionals to determine how well your kidneys are filtering waste from your blood. Because a direct measurement of GFR is complicated and invasive, doctors use mathematical formulas based on substances already in your blood.

The CKD-EPI 2021 Formula

Modern laboratories primarily use the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) 2021 equation. This updated version is preferred because it does not include a race variable, making it more accurate and equitable for all patients.

The calculation relies on three primary factors:

  • Serum Creatinine: A waste product from muscle breakdown that is filtered by the kidneys.
  • Age: Kidney function naturally declines as we get older.
  • Biological Sex: Men typically have higher muscle mass and higher baseline creatinine levels than women.

Understanding the Math

The logic follows a complex exponential decay model. For example, the formula for a female is:

eGFR = 142 × min(Scr/0.7, 1)-0.241 × max(Scr/0.7, 1)-1.200 × 0.9938Age × 1.012

Interpreting Your eGFR Results

Results are categorized into stages of kidney health:

eGFR Range Interpretation
90 or higher Stage 1: Normal kidney function
60 – 89 Stage 2: Mildly decreased function
30 – 59 Stage 3: Moderate decrease (Possible CKD)
15 – 29 Stage 4: Severe decrease in function
Less than 15 Stage 5: Kidney failure

Disclaimer: This calculator is for educational purposes only. Always consult a medical professional for diagnosis and treatment plans.

function calculateEGFR() { var scr = parseFloat(document.getElementById('serum_creatinine').value); var age = parseFloat(document.getElementById('patient_age').value); var gender = document.getElementById('patient_gender').value; var resultDiv = document.getElementById('egfr_result_container'); var valueSpan = document.getElementById('egfr_value'); var interpretationSpan = document.getElementById('egfr_interpretation'); if (isNaN(scr) || isNaN(age) || scr <= 0 || age = 90) { statusText = "Stage 1: Normal Kidney Function"; statusColor = "#155724"; bgColor = "#d4edda"; } else if (finalResult >= 60) { statusText = "Stage 2: Mildly Decreased Function"; statusColor = "#856404"; bgColor = "#fff3cd"; } else if (finalResult >= 30) { statusText = "Stage 3: Moderate Decrease (Possible CKD)"; statusColor = "#856404"; bgColor = "#ffeeba"; } else if (finalResult >= 15) { statusText = "Stage 4: Severe Decrease in Function"; statusColor = "#721c24"; bgColor = "#f8d7da"; } else { statusText = "Stage 5: Kidney Failure"; statusColor = "#ffffff"; bgColor = "#721c24"; } interpretationSpan.innerText = statusText; interpretationSpan.style.color = statusColor; interpretationSpan.style.backgroundColor = bgColor; }

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