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Abdul Mannan: Here’s when Your POC INR Machine Misleads You

Abdul Mannan/LinkedIn

May 10, 2026, 15:33

Abdul Mannan: Here’s when Your POC INR Machine Misleads You

Abdul Mannan, Consultant Haematologist at Betsi Cadwaladr University Health Board, shared a post on LinkedIn:

“Your POC INR device will give you a number on a DOAC patient.

Confidently. Immediately. Completely useless.

This is one of the most common ward-level anticoagulation errors I see.

Here’s when your POC INR machine misleads you:

Triple-positive APS (LA + aCL + anti-β2GPI): may dramatically underestimate true anticoagulation intensity
DOACs: the device still displays a result. That result means nothing.
Haematocrit below 25% or above 55%: mechanical detection methods are especially affected
High paraprotein: viscosity throws off clot-based chemistries

Why does this happen?

Most modern POC devices (CoaguChek XS family) don’t measure fibrin formation. They measure thrombin generation via a synthetic substrate.

That’s the source of the interference.

Successive BSH and ISTH guidance has been explicit: Triple-positive APS patients must not be monitored with POC INR devices.

I’ve just published a free interactive reference covering all 5 major UK POC INR devices, the electrochemical principle (with an animated amperometric cell diagram), a full pre/post-analytical procedure, limitations taxonomy, and the safety non-negotiables.

Free to use, no login.

What’s the trickiest POC INR case you’ve had to escalate?”

Other posts from Abdul Mannan on Hemostasis Today.