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Abdul Muqtadir Abbasi: How Do Hematologists Know Which Coagulation Factor Is the Problem?
Sep 18, 2026, 14:52

Abdul Muqtadir Abbasi: How Do Hematologists Know Which Coagulation Factor Is the Problem?

Abdul Muqtadir Abbasi, Assistant Consultant at King Faisal Specialist Hospital and Research Center, shared a post on LinkedIn:

”How do hematologist know, which coagulation factor is the problem?

PT, aPTT and Fibrinogen: a practical clotting-factor algorithm

PT prolonged, aPTT normal

  • Think FVII deficiency
  • Check FVII assay

PT normal, aPTT prolonged

  • Think VIII, IX, XI, XII
  • Do a mixing study

Corrects means factor deficiency, followed by factor assays

Fails to correct means inhibitor/heparin, so investigate further

PT prolonged and aPTT prolonged

  • Think common pathway (II, V, X, fibrinogen) or multiple-factor deficiency
  • Check fibrinogen, D-dimer, platelets, LFTs and medication history

PT prolonged and aPTT prolonged and fibrinogen decreased

  • Strongly consider DIC/consumption

Rule of thumb: Screen, followed by mixing study, followed by factor assay, followed by confirmation of the diagnosis

So what exactly is mixing studies?

Lets make it very simple.

We take patient plasma and add normal plasma with it.

If there is a deficiency of a certain factor, the addition of normal plasma with patient plasma will correct the deficiency and pt/ptt will become normal, which will prove deficiency, that can be confirmed by factor assay.

If addition if it doesnt correct pt/ptt, means there is actually an inhibitor of that particular factor that is also not allowing combining the normal plasma work.”

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