What is the minimum acceptable Kt/V?

KDOQI guidelines recommend a single-pool Kt/V of at least 1.2 per session for thrice-weekly hemodialysis. Values below 1.2 indicate inadequate clearance and the session should be reviewed.

What is the Daugirdas second-generation formula?

Kt/V = -ln(R - 0.008 × t) + (4 - 3.5 × R) × (UF / W), where R = post-BUN / pre-BUN, t = session time in hours, UF = ultrafiltration in liters, and W = post-weight in kg.

What is URR and how does it relate to Kt/V?

URR (urea reduction ratio) = (1 - post-BUN / pre-BUN) × 100. A URR ≥ 65% roughly corresponds to Kt/V ≥ 1.2. Kt/V is more accurate because it accounts for ultrafiltration and session time.

Should I use pre- or post-dialysis weight for W?

The Daugirdas formula uses post-dialysis (dry) weight. Using pre-dialysis weight will slightly underestimate Kt/V.

Does this calculate equilibrated (eKt/V) or single-pool (spKt/V)?

This tool calculates single-pool Kt/V (spKt/V) using the Daugirdas second-generation equation, which is the most widely used clinical standard.

Kt/V Dialysis Calculator

Name: Kt/V Dialysis Calculator
Availability: InStock
Author: Nham Vu

Calculate Kt/V dialysis adequacy with the Daugirdas second-generation formula to confirm a hemodialysis session met the minimum clearance target.

Session Inputs

Pre-BUN (mg/dL)

Post-BUN (mg/dL)

Pre-weight (kg)

Post-weight (kg)

Session duration (minutes)

Ultrafiltration (UF) is derived from the weight difference (pre − post weight). No separate UF entry needed.

Results

Enter values and click Calculate

Summary

Calculate Kt/V dialysis adequacy with the Daugirdas second-generation formula to confirm a hemodialysis session met the minimum clearance target.

How it works

Enter pre- and post-dialysis BUN (blood urea nitrogen) values.
Enter pre- and post-dialysis patient weight in kilograms.
Enter session duration in minutes and ultrafiltration volume in liters.
The calculator applies the Daugirdas second-generation formula.
A Kt/V ≥ 1.2 per session meets the minimum KDOQI adequacy target.
URR (urea reduction ratio) is also shown as a secondary adequacy metric.

Use cases

Verify a thrice-weekly hemodialysis session delivered adequate urea clearance.
Compare Kt/V trends over multiple sessions to detect declining dialyzer performance.
Screen patients whose symptoms suggest under-dialysis.
Document session adequacy for nephrology chart audits.
Educate patients on how dialysis dose is measured and what the targets mean.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu