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Mostafa Hammam: Three Different Platelet Defects – One Common Symptom
Mostafa Hammam/LinkedIn
Sep 19, 2026, 01:39

Mostafa Hammam: Three Different Platelet Defects – One Common Symptom

Mostafa Hammam, Blood Bank Laboratory Technician at Specialized Medical Centers in Egypt, shared a post on LinkedIn:

“Three patients walk in with the same symptom — excessive bleeding. One’s platelets won’t talk to each other. One’s platelets won’t touch the vessel wall. One is missing the glue holding the whole system together. Same symptom, three completely different failures.

In Hematology and Hemostasis, distinguishing between primary hemostasis disorders can feel tricky on board exams like the ASCPi (MLS or MLT). But once you categorize whether the defect is in platelet-to-platelet binding (aggregation) or platelet-to-vessel binding (adhesion), everything clicks!

Here is a high-yield breakdown of the big three platelet defects:

1.Glanzmann Thrombasthenia – The Aggregation Failure

  • The Mechanism: Platelet-to-platelet problem.
  • Defect: Deficiency or dysfunction of the Glycoprotein IIb or IIIa (GP IIb or IIIa) receptor.

Key Findings:

  • Platelets cannot bind to fibrinogen to cross-link with each other.
  • Aggregation is Impaired with ADP, Collagen, and Epinephrine.
  • Ristocetin response is normal.
  • Platelet count and morphology are normal.

2.Bernard-Soulier Syndrome – The Adhesion Failure

  • The Mechanism: Platelet-to-vessel wall problem.
  • Defect: Deficiency of the Glycoprotein Ib (GP Ib or IX and V) receptor complex.

Key Findings:

  • Platelets cannot adhere to exposed subendothelial collagen.
  • Aggregation with Ristocetin is impaired (and does not correct with normal plasma).
  • Hallmark Smear Finding: Thrombocytopenia with giant platelets.

3.Von Willebrand Disease (vWD) – The Missing Glue

  • The Mechanism: The ‘middleman’ bridging vessel to platelet is missing.
  • Defect: Quantitative or qualitative deficiency of von Willebrand Factor (vWF).

Key Findings:

  • Platelet receptors are normal, but the molecular glue is deficient.
  • Ristocetin aggregation is impaired, but corrects upon mixing with normal plasma!
  • Secondary effect: vWF carries and stabilizes Factor VIII, so patients may also present with a prolonged aPTT.

Glanzmann: Defect is GP IIb or IIIa, Ristocetin is Normal, Agonists are abnormal

Bernard-Soulier: Defect is GP Ib, Ristocetin is Abnormal, Smear – Giant Platelets

vWD: Defect is vWF, Ristocetin is Abnormal (Corrects with plasma), Factor VIII or aPTT affected

What is your top memory trick for keeping GP Ib vs. GP IIb/IIIa straight during exam prep?

Let’s discuss below!”

Mostafa Hammam

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ADP aPTT ASCPi Bernard–Soulier Syndrome bleeding disorders Blood Collagen Epinephrine Factor VIII fibrinogen Glanzmann thrombasthenia GP IIb GP IIb/IIIa receptor Health Hematology Hemostasis Hemostasis News Hemostasis Today Medicine Mostafa Hammam Platelet platelet adhesion Platelet Aggregation ristocetin thrombocytopenia thrombosis Von Willebrand Disease Von Willebrand Factor VWD VWF
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