FRCPath Haem Part 1 MCQ-Haemostasis 400
- amirhayat2527
- 1 day ago
- 0 min read
A 7yr-old boy with severe haemophilia A with inhibitors is started on Emicizumab for prophylaxis. Which of following tests is not affected by Emicizumab?
aPTT
One-stage factor VIII assay
TEG
PT/INR
Correct Answer: PT/INR
Tests commonly affected by Emicizumab
Activated Partial Thromboplastin Time (aPTT)
Prolonged aPTT is normalized artificially by Emicizumab because it mimics factor VIII.
So, aPTT-based factor VIII assays are unreliable.
One-stage FVIII assay (aPTT-based)
Strongly affected. Emicizumab overestimates FVIII activity, giving falsely high results.
Clot-based Bethesda assay for inhibitors
Standard aPTT-based Bethesda assays cannot reliably measure inhibitors in the presence of Emicizumab.
Tests not affected by Emicizumab
Chromogenic FVIII assay using bovine reagents
Not affected. Bovine FIX and FX are used, and Emicizumab does not recognize bovine factors, so this assay gives an accurate FVIII activity.
Thrombin generation assay
May be influenced depending on assay setup, but generally less affected than aPTT.
PT/INR
Emicizumab does not affect the extrinsic pathway,…