Abdul Mannan: The Hidden Role of Factor XIII in Protecting Clot Stability
Abdul Mannan, Consultant Haematologist at Betsi Cadwaladr University Health Board, shared a post on LinkedIn:
“Most people think FXIII deficiency is a structural problem.
A missing glue.
It is not.
It is a fibrinolytic catastrophe in slow motion.
Your patient’s wound looked fine.
Bleeding stopped. They went home.
48 hours later: severe haemorrhage.
The clot is gone.
PT, aPTT, and thrombin time?
All completely normal.
This is FXIII deficiency.
And it behaves like nothing else in haemostasis.
Here is why:
Factor XIIIa does two jobs most people only half-remember:
- It cross-links fibrin (γ-γ dimers, α-polymers) for structural strength
- It covalently anchors α₂-antiplasmin into the clot via an isopeptide bond (Gln14 on α₂AP – Lys303 on the fibrin Aα-chain)
That second job is the one that keeps the clot alive.
Without FXIIIa, α₂-antiplasmin stays loosely bound only.
During clot retraction, it gets physically squeezed out.
The un-crosslinked fibrin mesh is left completely exposed to plasmin and tPA.
Plasmin works slowly but completely unopposed.
Over 24 to 48 hours, the plug dissolves.
This is not a coagulation failure.
It is a localised hyperfibrinolytic crisis.
Standard coagulation screens will never catch it.
You need a specific FXIII assay.
Classic presentations:
- Umbilical stump bleeding in neonates
- Wound re-bleeding post-operatively
- Intracranial haemorrhage, recurrent miscarriage.
Infographic below shows the full mechanism.
What is the rarest factor deficiency you have diagnosed in your practice?”
Other posts featuring Abdul Mannan on Hemostasis Today.
-
Jul 13, 2026, 20:17Julia R. Coleman: Fantastic First Day at ISTH 2026
-
Jul 13, 2026, 20:11Ruah Alyamany: Combination Therapy Improves Quality of Life in ITP
-
Jul 13, 2026, 19:47Brian O Mahony: Two-Year Results of BBM-H901 Gene Therapy Presented at ISTH 2026
-
Jul 13, 2026, 19:37Sara Zalghout: Connecting With Colleagues From All Over the World at ISTH 2026
-
Jul 13, 2026, 18:54Alfonso J. Tafur: New Evidence on Perioperative Anticoagulation in Cancer at ISTH 2026
-
Jul 13, 2026, 18:42Jessica Garcia: Thrombin Generation in Type 3 VWD With an Inhibitor on Emicizumab
-
Jul 13, 2026, 18:19Fionnuala Ní Áinle: High-Quality Evidence for DVT Diagnosis in Pregnancy at ISTH 2026
-
Jul 13, 2026, 17:39Pascal Boulanger: Send a Postcard to Your Lab Staff From ISTH 2026
-
Jul 13, 2026, 17:21Stefano Navarro: Presenting Our Recently Published Article at ISTH 2026