Creatinine Calculator

Creatinine & GFR Calculator (CKD-EPI 2009)

Enter your details and click 'Calculate GFR' to see your estimated Glomerular Filtration Rate.

function calculateGFR() { var creatinine = parseFloat(document.getElementById("creatinineLevel").value); var age = parseInt(document.getElementById("age").value); var sexMale = document.getElementById("sexMale").checked; var sexFemale = document.getElementById("sexFemale").checked; var isAfricanAmerican = document.getElementById("isAfricanAmerican").checked; if (isNaN(creatinine) || creatinine <= 0 || isNaN(age) || age < 18) { document.getElementById("gfrResult").innerHTML = "Please enter valid positive numbers for Creatinine Level and Age (minimum 18 years)."; return; } var GFR; var kappa; // kappa is 0.7 for females, 0.9 for males var alpha; // alpha is -0.329 for females <= kappa, -0.411 for males <= kappa if (sexFemale) { kappa = 0.7; if (creatinine <= kappa) { alpha = -0.329; GFR = 144 * Math.pow(creatinine / kappa, alpha) * Math.pow(0.993, age); } else { alpha = -1.209; GFR = 144 * Math.pow(creatinine / kappa, alpha) * Math.pow(0.993, age); } } else if (sexMale) { kappa = 0.9; if (creatinine = 90) { gfrCategory = "Stage 1: Normal or High GFR"; gfrColor = "green"; } else if (GFR >= 60 && GFR = 45 && GFR = 30 && GFR = 15 && GFR < 30) { gfrCategory = "Stage 4: Severely decreased GFR"; gfrColor = "red"; } else { // GFR < 15 gfrCategory = "Stage 5: Kidney Failure"; gfrColor = "darkred"; } document.getElementById("gfrResult").innerHTML = "Your estimated GFR is: " + GFR.toFixed(2) + " mL/min/1.73m²" + "This falls into: " + gfrCategory + "" + "Note: This calculator uses the CKD-EPI (2009) equation. Consult a healthcare professional for diagnosis and treatment."; }

Understanding Creatinine and Glomerular Filtration Rate (GFR)

Creatinine is a waste product generated from muscle metabolism. It's produced at a relatively constant rate by the body and is filtered out of the blood by the kidneys. Because healthy kidneys efficiently remove creatinine, blood creatinine levels are a good indicator of kidney function. When kidney function declines, creatinine levels in the blood tend to rise.

What is GFR?

Glomerular Filtration Rate (GFR) is considered the best overall measure of kidney function. It estimates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. A higher GFR indicates better kidney function, while a lower GFR suggests that the kidneys are not filtering waste products as effectively as they should.

Directly measuring GFR is complex and usually involves specialized tests. Therefore, GFR is often estimated using formulas that take into account factors like serum creatinine levels, age, sex, and sometimes race. The calculator above uses the widely accepted CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) 2009 equation.

How to Use the Creatinine & GFR Calculator

Our calculator simplifies the process of estimating your GFR. Simply input the following information:

1. Creatinine Level (mg/dL): This is typically obtained from a blood test.
2. Age (years): Your age in years.
3. Sex: Select whether you are Male or Female.
4. African American: Check this box if you identify as African American. The CKD-EPI equation includes a race factor, which has been a subject of ongoing discussion in medical communities regarding its clinical appropriateness and potential for health disparities.

After entering the details, click the "Calculate GFR" button to get your estimated GFR in mL/min/1.73m².

Interpreting Your GFR Results (Stages of Chronic Kidney Disease)

The estimated GFR helps classify the stage of chronic kidney disease (CKD):

• GFR ≥ 90 mL/min/1.73m²: Stage 1 (Normal or High GFR) – Kidney damage with normal or increased GFR.
• GFR 60-89 mL/min/1.73m²: Stage 2 (Mildly decreased GFR) – Kidney damage with mildly decreased GFR.
• GFR 45-59 mL/min/1.73m²: Stage 3a (Mild-to-moderately decreased GFR) – Mild to moderate loss of kidney function.
• GFR 30-44 mL/min/1.73m²: Stage 3b (Moderately-to-severely decreased GFR) – Moderate to severe loss of kidney function.
• GFR 15-29 mL/min/1.73m²: Stage 4 (Severely decreased GFR) – Severe loss of kidney function.
• GFR < 15 mL/min/1.73m²: Stage 5 (Kidney Failure) – Kidney failure, often requiring dialysis or kidney transplant.

It's important to note that a GFR below 60 mL/min/1.73m² for three months or more is indicative of chronic kidney disease, regardless of the presence of kidney damage.

Factors Affecting Creatinine and GFR

Several factors can influence creatinine levels and, consequently, estimated GFR:

• Muscle Mass: Individuals with more muscle mass (e.g., bodybuilders) may have higher creatinine levels even with normal kidney function.
• Diet: A high-protein diet can temporarily increase creatinine levels.
• Hydration: Dehydration can lead to higher creatinine levels.
• Medications: Certain drugs can affect creatinine levels or GFR directly.
• Age: GFR naturally declines with age.

Realistic Examples

Let's look at a few examples using the calculator:

1. Example 1: Healthy Individual
   • Creatinine Level: 0.8 mg/dL
   • Age: 30 years
   • Sex: Female
   • African American: No
   • Estimated GFR: Approximately 105.20 mL/min/1.73m² (Stage 1)
2. Example 2: Mildly Decreased Kidney Function
   • Creatinine Level: 1.3 mg/dL
   • Age: 60 years
   • Sex: Male
   • African American: No
   • Estimated GFR: Approximately 62.15 mL/min/1.73m² (Stage 2)
3. Example 3: Moderately Decreased Kidney Function (with race factor)
   • Creatinine Level: 2.0 mg/dL
   • Age: 55 years
   • Sex: Female
   • African American: Yes
   • Estimated GFR: Approximately 38.90 mL/min/1.73m² (Stage 3b)

Important Disclaimer

This Creatinine & GFR Calculator is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment. The results provided by this calculator are estimates and may not reflect your actual kidney function.