What KT/V value is considered adequate?

KDOQI guidelines recommend a minimum single-pool KT/V of 1.2 for three-times-per-week hemodialysis. Values above 1.4 are considered optimal. This calculator uses the Daugirdas second-generation formula, which closely approximates the more complex two-pool model.

How is dialyzer clearance (K) estimated?

Clearance is estimated with the formula K = Qb × (1 − e^(−KoA/Qb)) adjusted for dialysate flow, where KoA is the mass-transfer area coefficient. Because KoA is not directly entered, the tool derives an effective K from Qb, Qd, and the measured URR, which is the standard clinical approach when KoA is unknown.

What is URR and how is it used?

Urea Reduction Ratio (URR) = (pre-BUN − post-BUN) / pre-BUN × 100. A URR ≥ 65% is the minimum KDOQI threshold for adequacy. The calculator shows URR alongside KT/V so you can verify both markers.

Is this tool a substitute for clinical judgment?

No. This calculator uses simplified models and population-average kinetic assumptions. Always confirm adequacy with laboratory-measured BUN and consult a nephrologist for clinical decisions.

What units should I enter?

Blood flow and dialysate flow in mL/min, session time in minutes, ultrafiltration volume in liters, BUN in mg/dL, and patient weight in kilograms.

Dialysis Clearance Calculator

Name: Dialysis Clearance Calculator
Availability: InStock
Author: Nham Vu

Calculate dialyzer clearance (mL/min) and KT/V adequacy index for hemodialysis sessions from blood flow, dialysate flow, and treatment parameters.

Session Parameters

Blood Flow Rate (Q_b) mL/min

Dialysate Flow Rate (Q_d) mL/min

Session Duration minutes

Ultrafiltration Volume (UF) L

Pre-dialysis BUN mg/dL

Post-dialysis BUN mg/dL

Patient Weight (post-dialysis) kg

KT/V Adequacy

—

0 Min 1.2 2.0+

Dialyzer Clearance (K)

—

mL/min

URR

—

% (target ≥65%)

Volume of Distribution (V)

—

liters

Session Time (T)

—

hours

Daugirdas Second-Generation Formula

KT/V = −ln(R − 0.008 × t)

+ (4 − 3.5 × R) × UF / W

R = post-BUN / pre-BUN • t = session time (hours) • UF = ultrafiltration (L) • W = post-dialysis weight (kg)

Summary

Calculate dialyzer clearance (mL/min) and KT/V adequacy index for hemodialysis sessions from blood flow, dialysate flow, and treatment parameters.

How it works

Enter blood flow rate (Qb), dialysate flow rate (Qd), and session duration.
Provide ultrafiltration volume removed during the session.
Enter pre-dialysis and post-dialysis BUN values along with patient dry weight.
The tool computes urea reduction ratio (URR) from BUN values.
Effective clearance K is estimated from Qb and Qd using a standard mass-transfer model.
KT/V is computed via the Daugirdas second-generation logarithmic formula and compared to KDOQI targets.

Use cases

Biomedical engineers verifying dialyzer performance against manufacturer specs.
Nephrology nurses checking session adequacy before documenting monthly KT/V.
Students learning dialysis kinetics and mass-transfer equations.
Researchers comparing clearance across different dialyzer membrane configurations.
Home hemodialysis patients reviewing session logs with their care team.
Technicians troubleshooting unexpectedly low URR results.

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu