Ifeanyichukwu Ifechidere: Coagulation Disorder or DOAC Interference?
Ifeanyichukwu Ifechidere, Specialist Biomedical Scientist at Sheffield Teaching Hospitals NHS Foundation Trust, shared a post on LinkedIn:
“Your patient may Not have protein C deficiency.
Your factor VIII result may Not be low.
And your lupus anticoagulant result may be completely fake.
The culprit?
DOACs.
This is one of the most dangerous misconceptions in coagulation testing:
Many people think DOACs only affect PT/APTT.
They don’t.
DOACs can interfere with almost every corner of haemostasis testing if you don’t recognise their presence first.
And this is where laboratory interpretation becomes critical.
I’ve seen cases where:
- Patients were wrongly labelled thrombophilic
- Factor assays appeared falsely reduced
- Lupus anticoagulant screens became falsely positive
- Natural anticoagulant results looked abnormal when they weren’t
All because one question was missed:
‘Is this patient on a DOAC?’
Here’s what many people don’t fully appreciate
DOACs interfere differently depending on:
- The specific drug
- The assay principle
- The reagent used
- Whether the method is clot-based or chromogenic
Which means the effect is Not uniform.
For example:
Factor Xa inhibitors (apixaban, rivaroxaban, edoxaban) can:
Falsely lower clot-based factor assays
Interfere with antithrombin assays
Distort protein C and protein S testing
Prolong dRVVT and mimic lupus anticoagulants
Dabigatran can:
Markedly prolong thrombin-based assays
Affect clot-based factor levels
Interfere with inhibitor studies
Cause misleading thrombophilia profiles
And this is the scary part:
Sometimes the laboratory result looks perfectly believable.
That’s what makes DOAC interference so dangerous.
Because if you don’t actively think about it…
You may interpret drug effect as disease.
This is why pre-analytical awareness matters just as much as analytical skill.
As biomedical scientists, we must constantly ask:
- What assay principle is being used?
- Is this method DOAC-sensitive?
- Could this ‘abnormality’ be interference instead of pathology?
Because in coagulation, understanding the limitations of the assay is just as important as understanding the disease itself.
And sometimes…
The most important coagulation diagnosis is recognising when the result should Not be trusted.
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