Single-pool Kt/V (Daugirdas II)
Enter pre- and post-dialysis BUN, session length, ultrafiltration volume, and post-dialysis weight to compute the delivered dialysis dose.
How to Use This Calculator
Obtain accurate laboratory measurements
Use pre- and post-dialysis BUN drawn from the same session. Post-BUN should be taken using the two-needle slow-flow technique.
Record session-specific parameters
Enter dialysis duration (hours), total ultrafiltration volume (litres), and post-dialysis weight (kg) for the same treatment.
Interpret alongside clinical context
Compare calculated Kt/V with guideline targets, review trends over time, and adjust dialysis prescription as needed.
Formula
Daugirdas II: Kt/V = −ln(R − 0.008 × t) + (4 − 3.5 × R) × (UF ÷ W)
R = Post-BUN ÷ Pre-BUN, t = dialysis time (hours), UF = ultrafiltration (litres), W = post-dialysis weight (kg).
Guideline targets: Kt/V ≥1.2 per session (minimum), ≥1.4 preferred for thrice-weekly haemodialysis.
Full Description
Single-pool Kt/V quantifies haemodialysis adequacy by estimating the fractional clearance of urea during a treatment. The Daugirdas II equation adjusts for urea rebound and ultrafiltration. Use this metric to monitor delivered dialysis, evaluate access performance, and guide adjustments to session length or dialyser efficiency. Assess trends rather than isolated values and combine with clinical assessment, interdialytic weight gain, and patient-reported symptoms.
Frequently Asked Questions
What if post-BUN was drawn too early?
Early sampling overestimates Clearance. Repeat with proper slow-flow sampling or use equilibrated Kt/V if rebound is significant.
Does this apply to high-frequency dialysis?
Daugirdas II targets thrice-weekly regimens. For other schedules, calculate standard or equilibrated Kt/V to account for frequency.
How do intradialytic hypotension episodes affect Kt/V?
Shortened treatments or reduced blood flow lower Kt/V. Document interruptions and adjust prescriptions to reach targets.
Should I use actual or dry weight?
Use post-dialysis weight (closest to dry weight) in the UF/W term for consistency with the validated formula.