If you need kt/v and urr and you already have volume of removed ultrafiltrate, post-dialysis weight, duration of dialysis, post-dialysis bun and pre-dialysis bun, this calculator does the substitution for you. It suits a quick check, a homework answer you want to confirm, or any figure you need to sanity test.
What Is the Kt/V Calculator?
The kt/v calculator gives you an estimate of kt/v and urr based on volume of removed ultrafiltrate, post-dialysis weight, duration of dialysis, post-dialysis bun and pre-dialysis bun.
It is a quick reference figure rather than a diagnosis, and it is most useful for tracking how a number moves over time rather than for interpreting a single reading.
How the Kt/V Estimate Is Worked Out
The calculation follows published reference relationships, so it is a reasonable approximation when the inputs are accurate. It assumes an average adult and does not account for individual variation.
If you are comparing two people, or the same person over a period of weeks, keep the method and the inputs identical. A change in the method can easily look like a change in the person.
What This Calculator Does Not Do
It does not diagnose anything, and it does not replace advice from a clinician. If a figure comes out at an extreme, or if it differs sharply from what you expect, that is a reason to speak to a professional rather than to adjust the inputs.
Nothing you type here is stored or sent anywhere. The whole calculation happens in your browser.
A Worked Example
Working through an example, with volume of removed ultrafiltrate set to 10, post-dialysis weight set to 5, duration of dialysis set to 2, the calculator returns urr of -9, and kt/v of -64.3. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out kt/v?
Enter volume of removed ultrafiltrate, post-dialysis weight, duration of dialysis, post-dialysis bun and pre-dialysis bun. The calculator then works through the relationship and reports kt/v and urr.
What does the kt/v actually calculate?
It takes volume of removed ultrafiltrate, post-dialysis weight, duration of dialysis, post-dialysis bun and pre-dialysis bun and converts them into kt/v and urr using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter volume of removed ultrafiltrate?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.
Do I have to fill in every field?
Only the fields a particular result depends on. If you leave one blank, the results that need it simply show a note instead of a number, and everything else still works.