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Hematology 2 (Lecture) > Primary Hemostasis & Platelet Function > Flashcards

Primary Hemostasis & Platelet Function Flashcards

1
Q

The body’s first line of defense against blood loss

A

platelet function

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2
Q

The property by which platelets bind non platelet surfaces such as subendothelial collagen

A

adhesion

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3
Q

Platelets adhere to collagen and undergo shape change from disc to spiny spheres

A

adhesion

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4
Q

ADHESION:
it aids in adhesion

A

Glycoprotein (GP) Ib and vWF

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5
Q

This is Primary Aggregation and reversible. This reaction is mediated by the release of platelet granules

A

adhesion

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6
Q

The property by which platelets bind to one another

A

aggregation

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7
Q

AGGREGATION:
Fibrinogen binds to GP IIb/IIIa receptors on adjacent platelets and joins them together in the presence of ______

A

ionized calcium

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8
Q

_______ essential for platelet aggregation, as evidenced by bleeding and compromised aggregation in patients with afibrinogenemia or in patients who lack the GPIIb/IIIa receptor (Glanzmann thrombasthenia)

A

fibrinogen binding

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9
Q

Platelets discharge the contents of their granules

A

secretion

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10
Q

The release of these granules constitutes a secondary aggregation that is irreversible

A

secretion

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11
Q

______ is released by platelets, which promotes vasoconstriction.

A

thromboxane A2

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12
Q

it amplifies the process

A

ADP

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13
Q

these are the aggregating agents most frequently used in clinical platelet aggregation

A

Epinephrine, collagen, ADP, and arachidonic acid

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14
Q

Initial evaluation includes a platelet count and slide estimate, with a reference value of ________

A

150,000 to 450,000/mm3

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15
Q

it is an effective in vivo screening test of platelet function by timing the length it takes for platelets to plug broken capillaries after a small cut is made in the forearm

A

bleeding time

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16
Q

RV for bleeding time

A

approx. 3-8 mins

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17
Q

Platelet aggregation is measured with a ______

A

platelet aggregometer

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18
Q

citrated, platelet-rich plasma
is stirred in the aggregometer while a light beam is passed through the suspension

A

basic principle

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19
Q

it retains aggregating properties but lacks clotting ability

A

γ-Thrombin

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20
Q

excessive bleeding that requires medical or physical intervention

A

hemorrhage

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21
Q

bleeding from a single location
which usually indicates injury, infection, tumor, or an isolated blood vessel defect

A

localized

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22
Q

bleeding from multiple sites,
spontaneous and recurring bleeds, or a hemorrhage that requires physical intervention

A

generalized

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23
Q

generalized bleeding in skin or at body orifices, most likely to be associated with thrombocytopenia (platelet count less than 150,000/microL, qualitative platelet disorders , von Willebrand disease (VWD), or vascular
disorders such as scurvy or telangiectasia

A

mucocutaneous

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24
Q

generalized bleeding (in soft tissue, muscles, joints, deep tissue)

A

anatomic

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25
Q

it is essential whenever a generalized mucocutaneous or anatomic bleed is detected

A

hemostasis laboratory testing

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26
Q

Besides a complete blood count that includes a platelet count, laboratory directors offer the:

A

prothrombin time (PT)
partial thromboplastin time (PTT)
activated partial thromboplastin time (APTT)
thrombin time (TT)
thrombin clotting time (TCT)
fibrinogen assay (FG)

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27
Q

Performed using the thromboelastograph (TEG) or thromboelastometry (TEM) using the rotational thromboelastometer (ROTEM)

A

thromboelastography

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28
Q

TEG and TEM are coagulometers that measure whole blood clotting, a process called ______

A

global hemostasis

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29
Q

Both report clot onset dynamics, clot strength, and fibrinolysis in _______

A

15-30 mins

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30
Q

(T/F)
TEG or TEM results require interpretation by experienced laboratory practitioners

A

true

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31
Q

Patient’s bleeding episodes begin after childhood

A

acquired

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32
Q

Are associated with some disease or physical trauma

A

acquired

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33
Q

Are not duplicated in relatives

A

acquired

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34
Q

Uncommon, occurring in fewer than 1 per 100 people

A

congenital

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35
Q

Are usually diagnosed in infancy or during the first years of life

A

congenital

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36
Q

Lead to recurrent hemorrhages that may be
spontaneous or may occur after minor injury or in unexpected locations, such as joints, body cavities, retinal veins and arteries, or the central nervous system

A

congenital

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37
Q

most common congenital deficiencies

A

VWD, factor VIII (FVIII, hemophilia A)
Factor IX deficiencies (FIX, hemophilia B)
Platelet function disorders

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38
Q

congenital deficiencies symptoms

A

petechiae, purpura, ecchymoses, epistaxis, and gingival bleeding

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39
Q

Caused by decreased or increased platelet production

A

quantitative platelet disorders

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40
Q

Platelet count of fewer than 100,000/mm3

A

thrombocytopenia

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41
Q

Decrease in platelets due to defective production of platelets in the bone marrow

A

thrombocytopenia

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42
Q

seen with the use of
radiation, alcohol, thiazide diuretics, chloramphenicol, and cancer chemotherapy

A

acquired disorders

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43
Q

present in 1% to 5% of infants at birth; most patients are preterm neonates born after pregnancies complicated by placental insufficiency or fetal hypoxia (preeclampsia and intrauterine growth restriction). These neonates have early-onset thrombocytopenia and impaired megakaryopoiesis in spite of increased levels
of thrombopoietin

A

neonatal disorders

44
Q

_______, which is commonly seen with splenomegaly and hypersplenism

A

splenic pooling

45
Q

______, which results in vascular shunting

A

hypothermia

46
Q

it is caused by excessive deposition of platelet aggregates in renal and cerebral vessels

A

Thrombotic thrombocytopenia purpura (TTP)

47
Q

as seen with systemic lupus
erythematosus (SLE)

A

vasculitis

48
Q

an autoimmune disorder

A

Idiopathic (immunologic) thrombocytopenia purpura (ITP)

49
Q

it occurs in children 2 to 6 years of age. There is a sudden onset of thrombocytopenia, which often follows viral infections, such as rubella, chickenpox, cytomegalovirus (CMV), and toxoplasmosis

A

acute ITP

50
Q

Acute ITP usually lasts for ______ with spontaneous remission in 80% of patients

A

2-6 weeks

51
Q

Platelet count is usually ______ in patients with acute ITP

A

<20,000/mm3

52
Q

it is caused by viral attachment and antigenic alteration of platelet membrane proteins that result in the formation of platelet autoantibodies, which are most often IgG. IgG-coated platelets are removed by macrophages in the spleen

A

acute ITP

53
Q

treatment of choice for acute ITP

A

corticosteroids

54
Q

it suppress macrophage phagocytic activity, decrease Fc-receptor function, and decrease antibody platelet binding.

A

steroids

55
Q

Splenectomy is rarely needed, and platelet transfusion is ineffective

A

acute ITP

56
Q

it occurs in adults 20 to 40 years of age. It is found in women three times more than in men and has a slow, asymptomatic onset of thrombocytopenia

A

chronic ITP

57
Q

chronic ITP can last from _______

A

months to years

58
Q

CHRONIC ITP:
Platelet count usually ranges from ______ to ______

A

30,000 to 80,000/mm3

59
Q

Chronic ITP is often associated with ____

A

SLE

60
Q

CHRONIC ITP:
_______ is the most common treatment because it decreases the number of macrophages with Fc receptors. Immunosuppressive chemotherapy with vincristine or vinblastine is used in severely affected patients

A

splenectomy

61
Q

it occurs in 1% to 2% of persons who receive blood transfusions. Production of antiplatelet antibodies by the recipient of platelet transfusions results in the destruction of platelets

A

posttransfusion purpura

62
Q

it is caused by maternal viremia (e.g., CMV or rubella) or maternal drug ingestion

A

isoimmune neonatal purpura

63
Q

Increase in circulating platelet counts >450,000/mm3

A

thrombocytosis

64
Q

it is associated with chronic
blood loss

A

iron-deficiency anemia

65
Q

it may be associated with high platelet counts

A

chronic inflammatory disease

66
Q

which may occur after a platelet depletion through a massive blood loss

A

rebound thrombocytosis

67
Q

Defects associated with surface components and intracellular components of platelets

A

qualitative platelet disorders

68
Q

Disorder of Platelet Adhesion

A

bernard-soulier syndrome (BSS)

69
Q

Due to an inherited quantitative or qualitative defect in the platelet glycoprotein (GP)Ib/IX/V complex

A

bernard-soulier syndrome (BSS)

70
Q

it is located on the short arm of chromosome 17

A

GP Ibα gene

71
Q

located on the long arm of chromosome 22

A

GP Ibβ gene

72
Q

located on the long arm or chromosome 3

A

GP IX and GP V genes

73
Q

clinical symptoms of BSS

A

epistaxis, gingival and cutaneous bleeding, and hemorrhage associated with trauma

74
Q

Laboratory diagnosis commonly results in a prolonged Ivy bleeding time, giant platelets, and thrombocytopenia

A

BSS

75
Q

Disorder of Platelet Aggregation

A

glanzmann’s thrombasthenia

76
Q

Described as a bleeding disorder associated with abnormal in vitro clot retraction and a normal platelet count

A

glanzmann’s thrombasthenia

77
Q

A homozygous autosomal recessive disorder in which one of two genes coding for either the membrane receptor glycoprotein IIb (GPIIb) or for GPIIIa is affected. Both genes are found on chromosome 17

A

glanzmann’s thrombasthenia

78
Q

Some platelet functional abnormalities are due to abnormalities in the granular fraction of the platelet

A

storage granules disorders

79
Q

Decreased numbers of dense granules due to an autosomal recessive trait caused by mutations in the HPS1 gene on chromosome 10q23 (controls functions involved in the production and control of melanosomes, platelet dense bodies, and lysosome)

A

hermansky-pudlak syndrome (HPS)

80
Q

Common symptoms consist of a triad phenotype of albinism, prolonged bleeding time, and the accumulation of ceroid pigment in lysosomal organelles

A

hermansky-pudlak syndrome (HPS)

81
Q

Other serious features include visual impairment, pulmonary fibrosis, inflammatory bowel disorder, and kidney disease

A

HPS

82
Q

Easy bruising, frequent nose bleeds, prolonged wound bleeding, heavy menstrual bleeding in females, and excessive bleeding with dental procedures are common

A

HPS

83
Q

Increased bleeding time test may be the first clue to differential diagnosis

A

HPS

84
Q

The most definite diagnosis can be found by electron microscope observation of the patient’s platelets and finding an absence of dense granules

A

HPS

85
Q

A generalized autosomal recessive genetic disorder with recurrent infections in combination with ocular, neurological, and skin manifestations caused by mutations in the lysosomal trafficking regulator gene (LYST) found on chromosome 1

A

chediak-higashi syndrome (CHS)

86
Q

Results in abnormal membrane fluidity, uncontrolled granule membrane fusion, and formation of giant cytoplasmic granules, and a lack of distinguishable dense granules in leukocytes, melanocytes, and platelets

A

chediak-higashi syndrome (CHS)

87
Q

Platelets have decreased dense granule ADP resulting in an increased ATP:ADP ratio

A

chediak-higashi syndrome

88
Q

The CBC with platelet count, Wright’s stained blood smear, bleeding time, platelet aggregation studies, ATP:ADP ratio measurements, and bone marrow biopsy

A

CHS

89
Q

A rare x-linked immunodeficiency disorder highlighted by thrombocytopenia, eczema, recurrent infections, and a predisposition for secondary leukemia or lymphoma

A

wiskott-aldrich syndrome (WAS)

90
Q

WAS
Caused by the deletion of a specific gene on the X chromosome called the _______ which is found exclusively in hematopoietic cells

A

WAS protein gene (WASp)

91
Q

WAS, alternatively called ______

A

eczema thrombocytopenia immunodeficiency syndrome

92
Q

The manifestations of the syndrome are localized hemorrhage, eczema, proneness to infection, and bloody diarrhea

A

WAS

93
Q

Laboratory diagnosis includes serum immunoglobulin levels, functional testing of humoral and cellular immunity, and CBC with cytoflow studies

A

WAS

94
Q

A rare autosomal recessive disorder characterized by the congenital absence of the radial bones (the most pronounced skeletal abnormality), numerous cardiac and other skeletal abnormalities, and thrombocytopenia (90% of cases)

A

thrombocytopenia with absent radii syndrome (TAR)

95
Q

A congenital platelet disease associated with thrombocytopenia and aggregation abnormalities characterized by a marked decrease or absence of platelet α-granules and specific α-granule proteins

A

storage pool disease or gray’s platelet syndrome

96
Q

AKA storage pool disease

A

gray’s platelet disease

97
Q

SPS/GPS
______ content was also decreased in the affected platelets as compared to normal

A

serotonin

98
Q

SPS/GPS
Newer methods have recently been reported for marking platelets with a green fluorescent dye _______ that is rapidly and selectively taken up by granules in platelets

A

mepacrine

99
Q

rare and genetic

A

cyclooxygenase deficiency

100
Q

May cause the bleeding time to increase by more than 30 minutes and the aggregation of platelets by fibrinogen absorbed onto the surfaces of the bypass circuit material

A

cardiopulmonary bypass

101
Q

Refers to deposition of large amounts of fibrin throughout the microcirculation, which results in a pathological activation of platelet aggregation and coagulation pathways

A

disseminated intravascular coagulation (DIC)

102
Q

Autoantibodies found in the patient’s plasma are directed against the phospholipid portion of phospholipoprotein components found as part of the platelet membrane surface, as well as the laboratory reagent used to perform the APTT

A

SLE - lupus-like anticoagulant

103
Q

Causes platelet aggregation abnormalities because of prostacyclin production and decreased platelet TXA2 production

A

hemolytic-uremic syndrome

104
Q

The most damaging metabolites to platelet function are thought to be urea, guanidinosuccinic acid, and phenolic acid

A

hemolytic-uremic syndrome

105
Q

Functional inhibition is most common with the group of drugs that inhibit platelet prostaglandin production, such as aspirin

A

drug-induced platelet abnormalities

Hematology 2 (Lecture) (3 decks)

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