Wolfgang Miesbach: Beyond Heparin – Anti-PF4 Disorders
Wolfgang Miesbach, Professor of Medicine at Frankfurt University Hospital, shared a post on LinkedIn about a recent article by Theodore E. Warkentin and Andreas Greinacher, published in NEJM, adding:
“Warkentin and Greinacher on platelet-activating anti-PF4 disorders (NEJM).
A patient with thrombosis and a falling platelet count – and no heparin anywhere in the chart. That used to close the case.
This review is about why it no longer does.
Heparin is only one trigger, and often not needed at all:
- Classic HIT – antibodies need heparin to activate platelets.
- Autoimmune HIT – triggered by heparin, but the antibodies also work without it. Stopping heparin does not stop the disease.
- Spontaneous HIT – no heparin at any point. Knee arthroplasty, bacterial infection.
- VITT – trigger is an adenovirus protein, from a vector vaccine or from natural infection.
- VITT-like MGTS – a monoclonal anti-PF4 protein keeps the process running for years.
Different triggers, one endpoint: immune complexes on PF4 – FcγIIa clustering – thrombosis with thrombocytopenia.
This decides your lab strategy.
Rapid immunoassays detect HIT antibodies but miss VITT antibodies.
Functional assays need added PF4 to become sensitive for VITT, and heparin in the assay can produce a false negative.
No single test covers the spectrum.
And your treatment.
Where antibodies act without heparin, a non-heparin anticoagulant alone is not enough.
Add Fc receptor–directed treatment: IVIG acutely, BTK inhibitors in chronic disease.
Thrombocytopenia plus thrombosis should raise the anti-PF4 question — heparin or no heparin.”
Title: Platelet-Activating Anti–Platelet Factor 4 Disorders
Authors: Theodore E. Warkentin, Andreas Greinacher

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