Note: Standard guidelines typically recommend a URR of 65% or higher for adequate hemodialysis.
function calculateUrrResult() {
// Get input elements using exact IDs
var preBunInput = document.getElementById("pre_bun_input");
var postBunInput = document.getElementById("post_bun_input");
var resultDisplay = document.getElementById("urr_result_display");
var valueOutput = document.getElementById("urr_value_output");
var statusMsg = document.getElementById("urr_status_msg");
// Parse values
var preVal = parseFloat(preBunInput.value);
var postVal = parseFloat(postBunInput.value);
// Validation Logic
if (isNaN(preVal) || isNaN(postVal)) {
alert("Please enter valid numbers for both Pre-dialysis and Post-dialysis BUN.");
resultDisplay.style.display = "none";
return;
}
if (preVal = preVal) {
alert("Post-dialysis BUN is typically lower than Pre-dialysis BUN. Please check your inputs.");
// We calculate anyway but warn the user
}
// URR Calculation: ((Pre – Post) / Pre) * 100
var urrPercentage = ((preVal – postVal) / preVal) * 100;
// Display Logic
resultDisplay.style.display = "block";
valueOutput.innerHTML = urrPercentage.toFixed(1) + "%";
// Interpretation Logic based on KDOQI guidelines
if (urrPercentage >= 65) {
statusMsg.innerHTML = "Adequate Dialysis (≥ 65%)";
statusMsg.className = "urr-status status-good";
} else {
statusMsg.innerHTML = "Inadequate Dialysis (< 65%)";
statusMsg.className = "urr-status status-bad";
}
}
What is Urea Reduction Rate (URR)?
The Urea Reduction Rate (URR) is a commonly used formula to measure the adequacy of hemodialysis treatment. It quantifies how effectively urea—a waste product formed in the liver and filtered by the kidneys—is removed from the blood during a dialysis session.
Monitoring URR is critical for patients with End-Stage Renal Disease (ESRD) to ensure they are receiving enough dialysis to prevent the buildup of toxins in the bloodstream.
How to Calculate URR
The calculation compares the Blood Urea Nitrogen (BUN) level before the treatment starts with the level after the treatment ends. The formula is straightforward:
Pre-dialysis BUN: The level of urea in the blood before the dialysis session begins.
Post-dialysis BUN: The level of urea in the blood immediately after the session concludes.
Note: The unit of measurement (mg/dL or mmol/L) does not affect the result, as long as both inputs use the same unit.
Understanding Your Results
According to the National Kidney Foundation's KDOQI (Kidney Disease Outcomes Quality Initiative) guidelines:
Target URR: A URR of 65% or higher is generally considered adequate.
Low URR: A value below 65% indicates that the dialysis treatment may not be removing enough waste.
URR vs. Kt/V
While URR is the simplest method to measure dialysis adequacy, another metric called Kt/V (Daugirdas formula) is often preferred by nephrologists because it accounts for the volume of water removed during dialysis (ultrafiltration) and residual kidney function. However, URR remains a valuable, quick, and easy-to-understand metric for patients and technicians.
Factors Affecting URR
If your Urea Reduction Rate is consistently low, your healthcare team may look at several factors to improve the efficiency of the treatment:
Treatment Time: Increasing the duration of the dialysis session.
Blood Flow Rate: Increasing the speed at which blood flows through the dialyzer.
Dialyzer Size: Using a larger filter with more surface area.
Needle Placement: Ensuring needles are placed correctly to avoid recirculation of cleaned blood.
Disclaimer
This calculator is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your nephrologist or dialysis care team regarding your lab results and treatment plan.