Whether you are estimating on the spot or checking a result somebody else gave you, the warfarin dosing calculator is the quickest way to get from current inr, bleeding, total warfarin dose, target inr and one way to change inr.
What Is the Warfarin Dosing Calculator?
The warfarin dosing calculator gives you an estimate of change inr based on current inr, bleeding, total warfarin dose, target inr and one way.
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 Warfarin Dosing 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 current inr set to 10, bleeding set to 0, total warfarin dose set to 5, the calculator returns change inr of 5,000. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out change inr?
Enter current inr, bleeding, total warfarin dose, target inr and one way. The calculator then works through the relationship and reports change inr.
What does the warfarin dosing actually calculate?
It takes current inr, bleeding, total warfarin dose, target inr and one way and converts them into change inr 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 current inr?
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.
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.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.