Exam 3 Flashcards
What aspect of hemostasis is affected by PLT disorders?
Primary hemostasis
What is the major disorder of PLT aggregation?
Glanzmann Thrombasthenia
Pathophysiology of Glanzmann-Thrombasthenia
a deficiency or abnormality of the PLT membrane GPIIb/GPIIa complex
Signs/Symptoms of Glanzmann Thrombasthenia
petechiae, purpura, menorrhagia, GI bleeding, hematuria
What population is Glanzmann Thrombasthenia commonly found in?
populations with high levels of inbreeding
What does PLT membrane GPIIb/IIIa bind?
fibrinogen, VWF, and fibronectin
What is the aggregation disorder that is associated with abnormal in vitro clot retraction and a normal PLT count?
Glanzmann Thrombasthenia
Homozygous or heterozygous conditions more severe?
Homozygous
What do the test results look like for Glanzmann Thrombasthenia? (PLT count, PLT morphology, PLT aggregation, PLT procoagulant activity tests)
PLT count - normal
PLT morphology - normal
PLT aggregation - lack of aggregation in response to all PLT activating agents
PLT procoagulant activity tests - diminished activity
Treatment of Glanzmann-Thrombasthenia
Transfusion of normal PLTs
What is the major disorder of PLT adhesion?
Bernard-Soulier (Giant Platelet) Syndrome
What is the pathophysiology of Bernard-Soulier Syndrome?
Missing GP Ib/IX/V complex; inability to bind VWF
Causes bleeding
Signs/Symptoms of Bernard-Soulier Syndrome
Ecchymoses, epistaxis, and gingival bleeding in childhood
What is the most frequent form of Bernard Soulier Syndrome?
Defects in synthesis or expression of GPIb alpha receptor
What will be seen in lab results for Bernard-Soulier Syndrome?
No response to ristocetin (ristocetin is an agonist to VWF and those with BSS cannot bind to VWF)
Treatment of Bernard-Soulier Syndrome
Afibrinolytic therapy (treat mucosal bleeding)
PLT transfusions (but can lead to developing alloantibodies)
What are Dense Granule Deficiencies caused by?
lack of ADP secretion
What deficiency is Hermansky-Pudlak Syndrome? What is it characterized by?
Dense granule deficiency; characterized by defective lysosomal function; platelets look like “swiss cheese”
What deficiency causes Chediak-Higashi Syndrome? What is it characterized by?
Dense granule deficiency; characterized by giant lysosomal granules
What deficiency causes Wiskott-Aldrich Syndrome? What is it characterized by?
Dense granule deficiency; characterized by microthrombocytopenia (microthrombocytes) and severe eczema
What deficiency causes Thrombocytopenia with Absent Radii Syndrome? What is it characterized by?
Dense granule deficiency; characterized by absence of radial bones
What deficiency causes Gray Platelet Syndrome? what is it characterized by?
alpha granule deficiency; characterized by absence of morphologically recognizable alpha granules in PLTs and large PLTs with a gray appearance
Which part of the platelet is affected in storage pool disorders?
Granule deficiencies (alpha and dense)
What is Scott Syndrome?
No phospholipid flip occurs; causes severely reduced or no thrombin generation
What is Stormorken Syndrome?
PLTs are always in an activated state; causes mild bleeding tendancy
What target does aspirin bind to?
COX-1 in an irreversible form?
What target does Clopidogrel, Prasugrel bind to?
ADP P2Y12 irreversibly
What target does Ticagrelor and Cangrelor bind to?
ADP P2Y12 reversibly
What target does Vorapaxar bind to?
Thrombin PAR-1
What target does Abciximab, Eptifibatide, and Tirofiban bind to?
GP IIb/IIIa
How does aspirin work as an antiplatelet drug?
Inhibits cyclooxygenase - leads to decreased thromboxane and decreased PLT activation
What do P2Y12 (ADP) receptor inhibitors do?
inhibits PLT activation and aggregation induced by ADP
What do GPIIb/IIIa receptor inhibitors do?
Interfere with ability to bind FBG