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Augustina Isioma Ikusemoro: Limitations of Mixing Studies in Differentiating Factor Deficiency from Inhibitors
Augustina Isioma Ikusemoro/LinkedIn
Apr 15, 2026, 15:01

Augustina Isioma Ikusemoro: Limitations of Mixing Studies in Differentiating Factor Deficiency from Inhibitors

Augustina Isioma Ikusemoro, Hematology and Transfusion Medicine Specialist at Sharjah Blood Transfusion and Research Center, shared a post on LinkedIn:

” ‘Your mixing study corrected… so it’s a factor deficiency, right?’

Not always.

This is one of the most common — and dangerous — assumptions in coagulation.

Because sometimes… your mixing study is misleading.

Let’s break it down:

A standard mixing study involves:

  • Patient plasma mixed with normal plasma in a one to one ratio
  • Immediate testing of APTT or PT

Correction indicates factor deficiency

No correction indicates inhibitor

Simple?

Not quite.

The problem: Time-dependent inhibitors

Some inhibitors don’t act immediately.

They are slow-acting (time-dependent) — often Factor VIII inhibitors

So what happens?

You perform an immediate mix: The APTT corrects

Looks like a factor deficiency…

But give it time.

You incubate at 37°C for 1–2 hours

Repeat the APTT

Now suddenly…

The correction disappears: APTT becomes prolonged again

What’s really happening?

These inhibitors:

  • Gradually neutralize clotting factors (especially Factor VIII)
  • Require time and temperature to exert their effect
  • This is why they’re called time- and temperature-dependent inhibitors

Clinical implications:

If you rely only on the immediate mix:

  • You may miss an acquired inhibitor
  • Delay diagnosis (e.g. acquired haemophilia)
  • Put patients at serious bleeding risk

Best practice:

Always perform:

  1. Immediate mixing study
  2. Incubated mixing study at 37°C for one to two hours
  3. And interpret both together.

Key takeaway:

A correcting mixing study does Not always mean factor deficiency.

Sometimes, it just means you didn’t wait long enough.”

Augustina Isioma Ikusemoro: Limitations of Mixing Studies in Differentiating Factor Deficiency from Inhibitors

Other posts featuring Augustina Isioma Ikusemoro on Hemostasis Today.

aPTT Augustina Isioma Ikusemoro bleeding disorders Factor VIII Inhibitors Health Hematology Hemophilia Hemostasis Hemostasis News Hemostasis Today Medicine mixing study
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