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hematalogy lecture > Test 6: Platelet Disorders > Flashcards

Test 6: Platelet Disorders Flashcards

1
Q

Defined as a plt. count < 1000,000/uL

less than _________ is critical

A

thrombocytopenia

20,000/ug (cue for transfusion)

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2
Q

Thrombocytopenia may result from …

A
  1. Defective production in bone marrow
  2. Disorders of distribution and dilution
  3. Destruction of platelets
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3
Q

What is the normal platelet count range?

A

150-450 x 10^9/L

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4
Q

What can cause defective production in the bone marrow?

A
  1. Decreased # of megakaryocytes
    -congenital (Fanconi’s anemia, May-Hegglin anomaly, maternal infection)
  2. Ineffective plt production (caused by impaired DNA synthesis
    -hereditary thrombocytopenia
    -Megaloblastic anemias
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5
Q

Different types of thrombocytopenia

A

-non-immune
-immune
-disorders of distribution and dilution of plt
-disorders from destruction of plt. (can result in DIC)

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6
Q

examples of non-immune thrombocytopenia

A

TTP, HUS, and DIC (aka Microangiopathic Thrombocytopenias)

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7
Q

What are the five types of immune thrombocytopenia?

A

-Idiopathic (or immune) Thrombocytopenia Purpura
-secondary autoimmune (ITP)
-drug-induced (Ex. HIT)
-post-transfusion
-neonatal alloimmune thrombocytopenias (NAIT)

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8
Q

Immune thrombocytopenias are associated with…

A

-Igs/compliment on plt. surface
OR
-production of specific anti-plt. Abs

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9
Q

-autoimmune bleeding disorder
-most common form of thrombocytopenia (<200,000/yr in US)

A

Immune (Idiopathic) Thrombocytopenic Purpura (ITP)

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10
Q

Characterized by deposition of Abs that bind to plt. surface (which are destroyed by phagocytosis in spleen and liver) in addition to abnormal B and T cells

A

Immune (Idiopathic) Thrombocytopenic Purpura (ITP)
-Acute ITP
-Chronic ITP

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11
Q

symptoms of both acute and chronic types of Immune (Idiopathic) Thrombocytopenic Purpura (ITP)?

A

-petechiae
-ecchymoses
-epitaxis
-menorrhagia

broad range of severity

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12
Q

In ITP, there are no real p.b. abnormalities except for decreased ___________ count.
How is diagnosis made?

A

platelet

by exclusion

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13
Q

laboratory findings with ITP include…

A

-increased MPV
-decreased plt. count (<100 x 10^9/uL)
-megakaryocytic hyperplasia
increased bleeding time
-plt-associated IgG

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14
Q

-usually rapid onset in children
-usually follows recovery from viral infection (CMV, rubella, chicken pox) or post-vaccination
-generally self-limiting (remission in 4-6 weeks)

A

Acute ITP

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15
Q

Plt. count is usually __________with acute ITP

A

<20,000/mm^3

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16
Q

Treatment for Acute ITP?

A

usually not needed, but intravenous immunoglobulin (IVIG), plt transfusion, and splenectomy may be needed

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17
Q

-usually occurs in adults (20-50y)
-three times more likely to be found in females

A

Chronic ITP

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18
Q

-slow, asymptomatic onset
-can be associated with SLE, HIV, or pregnancy-related
-fluctuating course (can last months to years)

A

Chronic ITP

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19
Q

antibodies target GP IB/IX or GP IIb/IIIa

A

Chronic ITP

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20
Q

Chronic ITP plt. range

A

30,000-80,000/mm3

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21
Q

Treatment of ITP?

A

depends on the severity,
-IVIG is treatment of choice
-prednisone and corticosteroids can be used

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22
Q

Drug-induced Thrombocytopenia can be caused by…

A

-quinidine/sulfonamide drugs, hapten-dependent antibodies, and drug-induced autoantibodies (>200 drugs responsible)

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23
Q

antibody induced by drug binds to GPIb/IX or GPIIb/IIIa

A

Quinidine/sulfonamide-induced thrombocytopenia

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24
Q

Occurs when a drug molecule is too small to react by itself, acts as a hapten, and bind to a glycoprotein to form a complex that acts as a complete antigen. Ex: penicillin

A

Drug-induced Thrombocytopenia:

Hapten-dependent antibodies

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25
Q

Drug-induced Autoantibodies:

Drug-induced thrombocytopenia that is so common it has its own name.

A

HIT (Heparin-Induced Thrombocytopenia)

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26
Q

Heparin binds to plt. factor ____

What does this cause?

A

4
-Circulating molecule released from plt’s alpha granules that binds
to heparin
This heparin-PF4 complex attaches to plt. and causes development of an anti-heparin/PF4 An*. Plt is destroyed when complex gets flagged by an Ab
-plt also gets activated, and will aggregate with other plts. causeing sudden deadly thromboemboli (with even further plt. consuption.)

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27
Q

Why is future use of heparin contraindicated with HIT.

A

–inlvoleves activation of coagulation system and thrombosis
-LMWH can trigger HIT but at a much lower risk

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28
Q

HIT is assayed using….

A

-Immunoassay for HIT antibody
-ELISA for heparin/anti-PF4 Abs
-Plt. aggregation using heparin

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29
Q

What is the therapy for HIT?

A

alternative anticoagulants after Protamine Sulfate treatment

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30
Q

-A rare disorder that develops about 1 week after transfusion of blood products, usually affecting females
-severe thrombocytopenia and moderate to severe hemorrhage that could be life-threatening

A

Post-transfusion Purpura

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31
Q

Post-transfusion Purpura:

alloantibodies to antigens on the plt or plt membranes of the transfused blood product….. alloantibody against ______ antigen.

A

HPA-1b

*subsequent transfusion will not increase plt count

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32
Q

with Post-transfusion Purpura, pt. is called “_______________________”.

A

refractory to plt. transfusion

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33
Q

What is the treatment for Post-transfusion Purpura?

A

IVIG

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34
Q

same as HDN (Hemolytic Disease of the Newborn), only with plts.

A

Neonatal Alloimmune Thrombocytopenia (NAIT)

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35
Q

caused when Mom lacks plt. Ag that fetus has, so Mom makes Ab against it. Then this IgG Ab crosses the placenta to destroy the fetal plts.

A

Neonatal Alloimmune Thrombocytopenia (NAIT)

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36
Q

With Neonatal Alloimmune Thrombocytopenia (NAIT), the majority of alloantibodies target _________.
Severity ranges from mild to life-threatening

A

GPIIb/IIIa

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37
Q

Non-Immune Thrombocytopenia results from…

A

-Plt. exposure to nonendothelial surface from activation of coagulation system
OR
-Plt. consumption by vascular injury-DIC, TTP, and Themolytic-uremic Syndrome all can lead to both hemorrhagic and thrombotic* episodes.

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38
Q

caused by excessive deposition of plt aggregates in renal and cerebral vessels (Vascular wall dysfunction*, disrupting the inert basement membrane that leads to platelet aggregation)

A

Thrombotic Thrombocytopenic Purpura (TTP)

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39
Q

who is more likely to get Thrombotic Thrombocytopenic Purpura (TTP)?

A

3 times more common in women than men

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40
Q

TTP is present with…

A

microangiopathic hemolytic anemia (MHA), thrombocytopenia, neurological symptoms, fever, and renal disease.

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41
Q

What organs are typically affected by TTP?

A

heart, brain, pancreas, and adrenals

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42
Q

TTP:

Normally, ultra-large vWF molecules (ULVWF) are cleaved by ______________ (a disintegrin and metalloprotease with thrombospondin type 1) as the ULVWF molecules are synthesized and released.

A

ADAMTS13

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43
Q

When ADAMTS13 is deficient, the ULVWF induces…

A

agglutination and formation of thrombi

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44
Q

TTP peripheral blood smear…

A

-marked decrease in plt
-RBC polychromasia
-RBC fragmentation
-nRBCs may be present

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45
Q

Treatment for TTP?

A

plasma exchange using FFP or cryo-poor plasma = lacking most fib., fibronectin, and vWF

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46
Q

-clinically resembles TTP, but occurs in children (6 m0-4 years) and is self-limiting

A

Hemolytic-uremic syndrome (HUS)

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47
Q

90% of Hemolytic-uremic syndrome (HUS) is caused by…

A

Shigella or E. coli organisms

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48
Q

Hemolytic-uremic syndrome (HUS) is present with…

A

hemolytic anemia, renal failure, thrombocytopenia, neurologic manifestations

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49
Q

treatment for Hemolytic-uremic syndrome (HUS)?

A

supportive care and plasma exchange if necessary

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50
Q

What are the lab findings with HUS?

A

-Decreased Hgb
-elevated retic count
-schistocytes

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51
Q

Thrombocytosis is a plt count over ___________. With over ______ plt seen per 100x feild.

A

450,000/uL, 23

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52
Q

Is primary or secondary Thrombocytosis more common?

A

secondary

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53
Q

Essential (Primary) Thrombocythemia is characterized by uncontrolled ______________ production and _____ ploriferation.

A

megakaryocyte, plt

54
Q

30% of RARS pt have _____________.

A

thrombocytosis

55
Q

-plt. count is usually greater than 1,000,000/uL
-plt. aggregation and morphology are abnormal*

A

Essential (Primary) Thrombocythemia

56
Q

Essential (Primary) Thrombocythemia:

abnormal plt aggregation seen with ___________, ____________, and ______________.

A

epinephrine, ADP, Collagen

57
Q

Secondary (Reactive) Thrombocytosis is a secondary response seen with…

A

-acute blood loss
-childbirth
-infection
-B.M. recovery
-alcohol withdrawal
-severe iron deficiency anemia

This is N. post-op phenomenon?

58
Q

What is often given post-op to combat thrombotic tendency brought on my secondary thrombocytosis

A

baby asprin

59
Q

-plt. count is around 450,000-800,000/uL with not change in plt function
-aggregation and morphalogy are normal

A

Secondary (Reactive) Thrombocytosis

*more common

60
Q

Qualitative plt. disorders can be inherited or acquired. What are common symptoms?

A

-menorrhagia
-bilateral petechiae and purpura
-epistaxis
-post-op bleeding

61
Q

with qualitative plt. disorders, ________ hemostasis is almost always okay.

A

secondary

-usually have normal plt. count = functional disorder
-plts. will clot eventually! (rare exception is severe hemorrhagic case of Glanzmann’s Thrombasthenia)

62
Q

two plt. adhesion disorders?

A

-Bernard-Soulier Disease
-Glanzmann Thrombasthenia

63
Q

Disorders of plt. secreation?

A

-Defects in dense granules
-Hermansky-Pudlak Syndrome
-Chediak-Higashi syndrome
-Wiskott-Aldrich Syndrome
-Storage Pool Disease
-Defects in alpha granules
-Gray Plt. Syndrome
-Thromboxane disorders

64
Q

Functional plt. disorder that may appear similar to ITP (i.e., thrombocytopenia, and giant plts)

A

Bernard-Soulier (Giant Platelet) Syndrome

65
Q

what is the autosomal recessive disorder in which the GpIb receptor missing from plt. surface?

this causes plts not to bind well to what?

A

Bernard-Soulier (Giant Platelet) Syndrome

vWF

66
Q

Bernard-Soulier (Giant Platelet) Syndrome causes ___________ adhesion to subendothelium and thus __________ efficiency of primary hemostasis.

A

decrased, decreased

67
Q

Bernard-Soulier Syndrome plt. do not respond to _________ and have diminished response to ___________.

A

ristocetin, thrombin

*some get as big as lymphs

68
Q

MPV is ________ with BSS.

A

increased

69
Q

Bernard-Soulier (Giant Platelet) Syndrome shows absent aggregation with ristocetin (that does NOT correct with…..

A

normal plasma addition

*resembles vWD, but vWD corrects with normal plasma

70
Q

Bernard-Soulier (Giant Platelet) Syndrome has mod-severe thrombocytopenia, giant platelets, and ____________ platelet function.

A

abnormal

71
Q

treatment for BSS?

A

plt. transfusions can be helpful (but can cause alloimmunization)

72
Q

-rare autosomal recessive disorder
-plts appear normal in number and appearance but have defective plt. receptor Gp2b3a (a result of >70 mutations)
-plt is unable to bind to Fbg

A

Glanzmann Thrombasthenia

73
Q

plts. use Fbg to help them stick together in 1st and 2nd wave of aggregation. This means Glanzmann Thrombasthenia plts. cant bind to each other ___________.
Adhesion and secretion is normal with GT.

A

securely

74
Q

Lab results for Glanzmann Thrombasthenia?

A

-marked prolonged bleeding time
-normal plt count and morphology
-poor clot retraction (old test)
-lack of response in plt aggregation (except when ristocetin is used, vWF binding to platelets is normal)

75
Q

Treatment for Glanzmann Thrombasthenia?

A

-plt transfusions
-hormonal therapy
-recombinant factor VIIa
-bone marrow transplants

76
Q

Inclove abnormal ADP release that can be due to:
-lack of granules
-deficient quantity of ADP stored in granules
-impaired secretion of normal granular contents.

A

Disorders of plt secretion (Storage Pool Disease)

77
Q

What is the classic aggregation result for Storage Pool Disease?

A

primary wave is normal, BUT secondary wave is abnormal (decreased or absent) to ADP, epinephrine, and decreased response to collagen. Normal response to ristocetin.

78
Q

Storage Pool Disease will have a _____________ bleeding time.

A

prolonged

79
Q

Deficiencies of Dense Granules:

(decreased ATP stores = ______________ disorders)

A

mild bleeding

80
Q

-caused by an autosomal recessive gene mutation
-has partial ocluocutaneous albinism, impaired vision, bruises easily, and difficulty clotting.

A

Hermansky-Pudlak Syndrome

81
Q

Hermansky-Pudlak Syndrome:

Has 7 known subtypes = ____________ mild bleeding tendency.

A

lifelong

82
Q

-caused by lack of dense granules (alpha granules are okay)

A

Hermansky-Pudlak Syndrome

83
Q

Hermansky-Pudlak Syndrome:

Marked dilation of __________________ -“Swiss cheese plt.”

A

open or surface-connected canalicular system

84
Q

Very rare-seen primarily in Puerto Ricans; typically fatal by middle age.

A

Hermansky-Pudlak Syndrome

85
Q

usually the worst of the qualitative inherited stroage pool diseases due to severity of bleeding

A

Hermansky-Pudlak Syndrome

86
Q

rare autosomal recessive disorder with a high infant mortality rate due to recurrent bacterial infection

A

Chediak-Higashi Anomaly or syndrome

87
Q

Chediak-Higashi Anomaly is a ____________ disease = lifelong mild bleeding tendency.

A

progressive

88
Q

characterized by partial oculocutaneous albinism, recurrent infections, neurological problems, and giant lysosomes

A

Chediak-Higashi Anomaly

89
Q

unusual because also seen in other species
and also have thrombocytopenia and neutropenia

A

Chediak-Higashi Anomaly

90
Q

Chediak-Higashi Anomaly is a mutation of the _______ gene- cytoplasmic granules tend to….

A

LYST
fuse in all cells.

91
Q

-sex-linked disorder (boys seldom survive adolescence
-lifelong bleeding tendency

A

Wiskott-Aldrich Syndrome (WAS)

92
Q

-very small plt, thrombocytopenia, and severe immune complications resulting from declining T cell quality and quantity.

A

Wiskott-Aldrich Syndrome (WAS)

93
Q

What is the classic symptomatic triad of Wiskott-Aldrich Syndrome (WAS)?

A

eczema, recurrent infections, and thrombocytopenia

94
Q

What causes thrombocytopenia with Wiskott-Aldrich Syndrome (WAS)?

A

by increased splenic sequestration, and destruction of defective plts. and ineffective thrombopoiesis

95
Q

Wiskott-Aldrich Syndrome and Chediak-Higashi Anomaly have decreased _______ stores.

A

ADP

96
Q

-lifelong mild bleeding tendency
-lack of alpha granules that make plts appear agranular
-characterized by large, blue-grey pts. on p.b. smear

A

Gray Platelet Syndrome

97
Q

due to NBEAL2 gene mutation

A

Gray Platelet Syndrome

98
Q

Gray Platelet Syndrome:

plt aggregation assays are…..

A

normal with mild clinical manifestations

99
Q

what is also termed “aspirin-like defects”

A

Thromboxane Pathway Disorders

100
Q

Thromboxane Pathway Disorders:

Contents of alpha and dense granules are normal, but ADP release or secretion is impaired due to…

A

-defects in the release of arachidonic acid from plt. p.m. phospholipids (Phospholipase A2 deficiency)
-Thromboxane (TXA2) synthesis deficiency

101
Q

produces a plt aggregation pattern similar to that of dense granules deficiency.

A

Thromboxane Pathway Disorders

102
Q

Thromboxane Pathway Disorders:

Classic aggregation result: primary wave is normal but…

A

secondary wave is abnormal (decreased or absent) to ADP, epinephrine, and decreased response to collagen.
Normal response to ristocetin.

103
Q

Where dose aspirin, ibuprofen, and NSAIDs “attack”?

A

cyclooxygenase (decreases)

104
Q

Prostaglandins and ___________ are both vital for continued plt. activation.

A

thromboxane A2

105
Q

Ibuprofen and Asprin permanently inhibit cyclooxygenase by ___________ it.

A

acetylating

106
Q

two acquired qualitative plt disorders?

A

chronic alcohol use and uremia (dialysis corrects)

107
Q

alcohol prevents plt. __________ to any roughened areas on endothelium, thereby preventing significant plaque buildup.

A

aggregation

108
Q

What are five vascular disorders due to hereditary connective tissue defects?

A
  1. Hereditary hemorrhagic Telangiectasia (HHT)
  2. Acquired (Senile) Purpura
  3. Henoch-Schonlein Purpura
  4. Ehlers-Danlos Syndrome
  5. Pseudoxanthoma Elasticum
109
Q

characterized by bleeding from telangiectasias (permanent, thin, dilated vascular malformations causing small red lesions);

A

Hereditary hemorrhagic Telangiectasia (HHT)

110
Q

most common inherited vascular bleeding disorder

A

Hereditary hemorrhagic Telangiectasia (HHT)

111
Q

so-called “allergic” purpura (probably autoimmune) in kids, with skin rash, edema, pruritus, and multifocal joint pain. (Due to IgA, IgE and C3 deposits in vasculature)

A

Henoch-Schonlein Purpura

112
Q

May be due to allergies or autoimmune drug-induced, or so-called “senile purpura” (the latter caused by age-related loss of collagen, elastin, and subcutaneous fat to support vessels).

A

Aquired (Senile) Purpura

113
Q

heterogeneous group of 11 different connective tissue (collagen) disorders with extreme tissue fragility, causing hyperextensible skin and hypermobile joints.

A

Ehlers-Danlos Syndrome

114
Q

defective elastin causes arterioles to be structurally defective

A

Pseudoxanthoma Elasticum

115
Q

Petechia, and prolonged bleeding from superficial wounds, are (by themselves) classically characteristic of what other category of disorders?

so these vascular diseases could also be expected to affect primarry ________.

A

(numerous) plt. disorders

hemostasis

116
Q

with Glanzzmann’s Thrombasthenia, clot retraction ….

A

absent or poor

117
Q

With Asprin-like defects:
adhesin is _______
ADP release is _________

A

normal, decreased

118
Q

qualitative plt. disorder:

No GpIb

A

Bernard-Soulier

119
Q

qualitative plt. disorder:

defective vWF

A

vWD (classic)

120
Q

qualitative plt. disorder:

Defective Gp2b3a

A

Glanzmann’s Thrombasthenia

121
Q

qualitative plt. disorder:

decreased ADP stores

A

Storage pool diseases

122
Q

qualitative plt. disorder:

Defective TXA2 and thus defective ADP release

A

Aspirin-Like Defects

123
Q

In which qualitative plt. defect is there normal adhesion?

A

only in aspirin-like defects

124
Q

What is the bleeding time like in qualitative plt disorders?

A

always increased

125
Q

Qualitative plt disorders:

what is the plt. count like in these disorders?

A

always normal

126
Q

In which qualitative plt. disorder is there abnormal clot retraction?

A

Glanzmann’s Thrombasthenia

Defective Gp2b3a (Fbg receptor) means secondary wave of aggregation is ineffective and clot cant be consolidated.

127
Q

With Bernard-Soulier, ristocetin is….

A

ABSENT (and does NOT correct with normal plasma)

128
Q

With VWD (plt-type and classic), ristocetin is….

A

variable! but corrects with normal plasma

129
Q

Which 2 classes of qualitative plt. disorders typically yield a normal first wave of aggregation, but an abnormal second wave?

A

Storage Pool Diseases and Aspirin-like defects

130
Q

Name the four storage pool diseases of plt.

A

Wiskott-Aldrich
Chediak-Higashi
Hermansky-Pudlak
Gray plt. syndromes

hematalogy lecture (35 decks)

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