URR Calculator
Calculate Urea Reduction Ratio to assess dialysis adequacy
Calculate URR
Choose Calculation Method
Urea level before dialysis session
Urea level after dialysis session
URR Results
Dialysis Adequacy Guidelines
Inadequate
Borderline
Adequate
Example Calculation
Dialysis Patient Example
Patient: 65-year-old on hemodialysis
Pre-dialysis urea: 40 mg/dL
Post-dialysis urea: 14 mg/dL
Dialysis session: 4 hours, 3 times per week
Calculation
URR = [(40 - 14) / 40] × 100%
URR = [26 / 40] × 100%
URR = 65%
Assessment: Adequate dialysis (URR ≥65%)
Corresponding Kt/V: -ln(1 - 0.65) ≈ 1.05
Medical Disclaimer
This calculator is for educational purposes only and should not replace professional medical assessment. URR monitoring and dialysis adequacy evaluation require clinical expertise and should always be supervised by qualified nephrologists and dialysis professionals. Inadequate dialysis can lead to serious health complications and increased mortality risk.
Quick Reference
Target Values
URR Formula
Improving URR
Increase dialysis session time
Optimize blood flow rate through dialyzer
Address vascular access problems
Ensure proper dialyzer function
Clinical Importance
URR <65% increases mortality risk
Regular monitoring improves outcomes
Simple assessment of dialysis quality
Correlates with patient survival
Understanding URR - Urea Reduction Ratio
What is URR?
The Urea Reduction Ratio (URR) is a simple measure of dialysis adequacy that quantifies the effectiveness of a dialysis treatment. It represents the percentage reduction in blood urea nitrogen (BUN) from the beginning to the end of a dialysis session.
Why is URR Important?
- •Simple assessment of dialysis effectiveness
- •Correlates with patient survival outcomes
- •Easy to calculate and monitor regularly
- •Helps optimize dialysis prescriptions
URR vs. Kt/V
URR Advantages
- • Simple calculation
- • No body weight needed
- • Easy to understand
- • Quick assessment
Kt/V Advantages
- • More comprehensive measure
- • Accounts for body size
- • Better for treatment planning
- • International standard
Clinical Guidelines and Standards
The URR target of ≥65% is based on clinical studies showing improved patient outcomes. This corresponds to a Kt/V of approximately 1.2. However, many dialysis units aim for higher targets to ensure adequate treatment despite variations in blood sampling and measurement.
Monitoring Schedule
- • Monthly URR assessment for all patients
- • More frequent monitoring for unstable patients
- • Assessment after any dialysis prescription changes
- • Quality assurance for dialysis adequacy programs