Creatinine and Calculated Glomerular Filtration Rate Test

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Creatinine and eGFR Calculator

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Understanding Creatinine and Estimated Glomerular Filtration Rate (eGFR)

Kidney function is vital for overall health, and two key indicators used to assess it are serum creatinine levels and the estimated Glomerular Filtration Rate (eGFR).

Serum Creatinine

Creatinine is a waste product generated from normal muscle metabolism. It is filtered out of the blood by the kidneys and excreted in urine. When kidney function declines, the kidneys are less efficient at filtering creatinine, leading to a buildup in the blood. Therefore, a higher serum creatinine level can indicate impaired kidney function.

Normal serum creatinine levels vary slightly depending on age, sex, muscle mass, and race. For adults, typical ranges might be:

  • Men: 0.7 to 1.3 mg/dL
  • Women: 0.6 to 1.1 mg/dL
It's important to note that these are general ranges, and your doctor will interpret your results in the context of your individual health.

Estimated Glomerular Filtration Rate (eGFR)

The Glomerular Filtration Rate (GFR) is a measure of how well your kidneys are filtering waste products from your blood. It represents the volume of fluid filtered by the glomeruli (tiny filtering units in the kidneys) per unit of time. A higher GFR indicates better kidney function.

Directly measuring GFR can be complex and is not routinely done. Instead, healthcare providers often use formulas to estimate GFR based on serum creatinine levels, along with other factors like age, sex, and race. This estimated value is called eGFR.

Several equations are used to calculate eGFR, with the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation being the most widely recommended. This calculator uses a version of the CKD-EPI equation.

Interpreting eGFR Values:

  • eGFR > 90 mL/min/1.73m²: Generally considered normal, but may be lower in certain conditions.
  • eGFR 60-89 mL/min/1.73m²: Mildly decreased GFR. Further investigation may be needed to determine the cause.
  • eGFR 30-59 mL/min/1.73m²: Moderately to severely decreased GFR. This can be a sign of Chronic Kidney Disease (CKD).
  • eGFR < 30 mL/min/1.73m²: Severely decreased GFR, indicating advanced kidney disease.

Regular monitoring of creatinine and eGFR is crucial for early detection and management of kidney disease. If your eGFR is consistently low, your doctor will work with you to slow the progression of kidney disease and manage any underlying causes.

Example Calculation

Let's consider a 62-year-old African American male with a serum creatinine of 1.2 mg/dL.

Using the calculator with these inputs:

  • Serum Creatinine: 1.2 mg/dL
  • Age: 62 years
  • Gender: Male
  • Race: African American

The calculated eGFR would be approximately 75 mL/min/1.73m². This suggests a mildly decreased kidney function, and his doctor might recommend further evaluation.

function calculateEGFR() { var serumCreatinine = parseFloat(document.getElementById("serumCreatinine").value); var age = parseFloat(document.getElementById("age").value); var gender = document.getElementById("gender").value; var race = document.getElementById("race").value; var resultDiv = document.getElementById("result"); resultDiv.innerHTML = ""; // Clear previous results if (isNaN(serumCreatinine) || isNaN(age) || serumCreatinine <= 0 || age 90) { interpretation = "Normal to mildly decreased kidney function. Continue regular monitoring."; } else if (egfr >= 60 && egfr = 30 && egfr <= 59) { interpretation = "Moderately to severely decreased kidney function. This may indicate Chronic Kidney Disease (CKD). Consult your doctor."; } else if (egfr < 30) { interpretation = "Severely decreased kidney function. This indicates advanced kidney disease. Urgent medical attention is recommended."; } resultDiv.innerHTML = "

Calculated eGFR

" + "eGFR: " + egfr + " mL/min/1.73m²" + "Interpretation: " + interpretation + ""; }

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