Thrombocytopenias and other platelet disorders

1. Big picture

Platelet disorders cause primary hemostasis failure, so the bleeding pattern is typically:

Petechiae + purpura + mucosal bleeding + epistaxis + gum bleeding + menorrhagia + immediate bleeding after procedures.

This is different from coagulation factor deficiency, which causes:

Deep muscle hematomas + hemarthroses + delayed post-operative bleeding.

The examiner wants you to separate two big groups:

Problem	Platelet count	Platelet function	Typical examples
Thrombocytopenia	Low	May be normal or abnormal	ITP, DIC, TTP/HUS, HIT, marrow failure, hypersplenism
Thrombocytopathy	Usually normal	Abnormal	Aspirin, clopidogrel, uremia, Glanzmann, Bernard-Soulier, von Willebrand disease

The textbook defines thrombocytopenia as decreased platelet number and emphasizes petechiae, purpura, mucosal bleeding, and possible life-threatening gastrointestinal or central nervous system bleeding. It also stresses that a low platelet count does not protect against thrombosis, especially in TTP, DIC, and HIT/HITT.

1. Big picture

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