Primary Hemostasis & Platelet Function Flashcards
1
Q
The body’s first line of defense against blood loss
A
platelet function
2
Q
The property by which platelets bind non platelet surfaces such as subendothelial collagen
A
adhesion
3
Q
Platelets adhere to collagen and undergo shape change from disc to spiny spheres
A
adhesion
4
Q
ADHESION:
it aids in adhesion
A
Glycoprotein (GP) Ib and vWF
5
Q
This is Primary Aggregation and reversible. This reaction is mediated by the release of platelet granules
A
adhesion
6
Q
The property by which platelets bind to one another
A
aggregation
7
Q
AGGREGATION:
Fibrinogen binds to GP IIb/IIIa receptors on adjacent platelets and joins them together in the presence of ______
A
ionized calcium
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
9
Q
Platelets discharge the contents of their granules
A
secretion
10
Q
The release of these granules constitutes a secondary aggregation that is irreversible
A
secretion
11
Q
______ is released by platelets, which promotes vasoconstriction.
A
thromboxane A2
12
Q
it amplifies the process
A
ADP
13
Q
these are the aggregating agents most frequently used in clinical platelet aggregation
A
Epinephrine, collagen, ADP, and arachidonic acid
14
Q
Initial evaluation includes a platelet count and slide estimate, with a reference value of ________
A
150,000 to 450,000/mm3
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
16
Q
RV for bleeding time
A
approx. 3-8 mins
17
Q
Platelet aggregation is measured with a ______
A
platelet aggregometer
18
Q
citrated, platelet-rich plasma
is stirred in the aggregometer while a light beam is passed through the suspension
A
basic principle
19
Q
it retains aggregating properties but lacks clotting ability
A
γ-Thrombin
20
Q
excessive bleeding that requires medical or physical intervention
A
hemorrhage
21
Q
bleeding from a single location
which usually indicates injury, infection, tumor, or an isolated blood vessel defect
A
localized
22
Q
bleeding from multiple sites,
spontaneous and recurring bleeds, or a hemorrhage that requires physical intervention
A
generalized
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
24
Q
generalized bleeding (in soft tissue, muscles, joints, deep tissue)
A
anatomic
25
it is essential whenever a generalized mucocutaneous or anatomic bleed is detected
hemostasis laboratory testing
26
Besides a complete blood count that includes a platelet count, laboratory directors offer the:
prothrombin time (PT)
partial thromboplastin time (PTT)
activated partial thromboplastin time (APTT)
thrombin time (TT)
thrombin clotting time (TCT)
fibrinogen assay (FG)
27
Performed using the thromboelastograph (TEG) or thromboelastometry (TEM) using the rotational thromboelastometer (ROTEM)
thromboelastography
28
TEG and TEM are coagulometers that measure whole blood clotting, a process called ______
global hemostasis
29
Both report clot onset dynamics, clot strength, and fibrinolysis in _______
15-30 mins
30
(T/F)
TEG or TEM results require interpretation by experienced laboratory practitioners
true
31
Patient’s bleeding episodes begin after childhood
acquired
32
Are associated with some disease or physical trauma
acquired
33
Are not duplicated in relatives
acquired
34
Uncommon, occurring in fewer than 1 per 100 people
congenital
35
Are usually diagnosed in infancy or during the first years of life
congenital
36
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
congenital
37
most common congenital deficiencies
VWD, factor VIII (FVIII, hemophilia A)
Factor IX deficiencies (FIX, hemophilia B)
Platelet function disorders
38
congenital deficiencies symptoms
petechiae, purpura, ecchymoses, epistaxis, and gingival bleeding
39
Caused by decreased or increased platelet production
quantitative platelet disorders
40
Platelet count of fewer than 100,000/mm3
thrombocytopenia
41
Decrease in platelets due to defective production of platelets in the bone marrow
thrombocytopenia
42
seen with the use of
radiation, alcohol, thiazide diuretics, chloramphenicol, and cancer chemotherapy
acquired disorders
43
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
neonatal disorders
44
_______, which is commonly seen with splenomegaly and hypersplenism
splenic pooling
45
______, which results in vascular shunting
hypothermia
46
it is caused by excessive deposition of platelet aggregates in renal and cerebral vessels
Thrombotic thrombocytopenia purpura (TTP)
47
as seen with systemic lupus
erythematosus (SLE)
vasculitis
48
an autoimmune disorder
Idiopathic (immunologic) thrombocytopenia purpura (ITP)
49
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
acute ITP
50
Acute ITP usually lasts for ______ with spontaneous remission in 80% of patients
2-6 weeks
51
Platelet count is usually ______ in patients with acute ITP
<20,000/mm3
52
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
acute ITP
53
treatment of choice for acute ITP
corticosteroids
54
it suppress macrophage phagocytic activity, decrease Fc-receptor function, and decrease antibody platelet binding.
steroids
55
Splenectomy is rarely needed, and platelet transfusion is ineffective
acute ITP
56
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
chronic ITP
57
chronic ITP can last from _______
months to years
58
CHRONIC ITP:
Platelet count usually ranges from ______ to ______
30,000 to 80,000/mm3
59
Chronic ITP is often associated with ____
SLE
60
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
splenectomy
61
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
posttransfusion purpura
62
it is caused by maternal viremia (e.g., CMV or rubella) or maternal drug ingestion
isoimmune neonatal purpura
63
Increase in circulating platelet counts >450,000/mm3
thrombocytosis
64
it is associated with chronic
blood loss
iron-deficiency anemia
65
it may be associated with high platelet counts
chronic inflammatory disease
66
which may occur after a platelet depletion through a massive blood loss
rebound thrombocytosis
67
Defects associated with surface components and intracellular components of platelets
qualitative platelet disorders
68
Disorder of Platelet Adhesion
bernard-soulier syndrome (BSS)
69
Due to an inherited quantitative or qualitative defect in the platelet glycoprotein (GP)Ib/IX/V complex
bernard-soulier syndrome (BSS)
70
it is located on the short arm of chromosome 17
GP Ibα gene
71
located on the long arm of chromosome 22
GP Ibβ gene
72
located on the long arm or chromosome 3
GP IX and GP V genes
73
clinical symptoms of BSS
epistaxis, gingival and cutaneous bleeding, and hemorrhage associated with trauma
74
Laboratory diagnosis commonly results in a prolonged Ivy bleeding time, giant platelets, and thrombocytopenia
BSS
75
Disorder of Platelet Aggregation
glanzmann's thrombasthenia
76
Described as a bleeding disorder associated with abnormal in vitro clot retraction and a normal platelet count
glanzmann's thrombasthenia
77
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
glanzmann's thrombasthenia
78
Some platelet functional abnormalities are due to abnormalities in the granular fraction of the platelet
storage granules disorders
79
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)
hermansky-pudlak syndrome (HPS)
80
Common symptoms consist of a triad phenotype of albinism, prolonged bleeding time, and the accumulation of ceroid pigment in lysosomal organelles
hermansky-pudlak syndrome (HPS)
81
Other serious features include visual impairment, pulmonary fibrosis, inflammatory bowel disorder, and kidney disease
HPS
82
Easy bruising, frequent nose bleeds, prolonged wound bleeding, heavy menstrual bleeding in females, and excessive bleeding with dental procedures are common
HPS
83
Increased bleeding time test may be the first clue to differential diagnosis
HPS
84
The most definite diagnosis can be found by electron microscope observation of the patient’s platelets and finding an absence of dense granules
HPS
85
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
chediak-higashi syndrome (CHS)
86
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
chediak-higashi syndrome (CHS)
87
Platelets have decreased dense granule ADP resulting in an increased ATP:ADP ratio
chediak-higashi syndrome
88
The CBC with platelet count, Wright’s stained blood smear, bleeding time, platelet aggregation studies, ATP:ADP ratio measurements, and bone marrow biopsy
CHS
89
A rare x-linked immunodeficiency disorder highlighted by thrombocytopenia, eczema, recurrent infections, and a predisposition for secondary leukemia or lymphoma
wiskott-aldrich syndrome (WAS)
90
WAS
Caused by the deletion of a specific gene on the X chromosome called the _______ which is found exclusively in hematopoietic cells
WAS protein gene (WASp)
91
WAS, alternatively called ______
eczema thrombocytopenia immunodeficiency syndrome
92
The manifestations of the syndrome are localized hemorrhage, eczema, proneness to infection, and bloody diarrhea
WAS
93
Laboratory diagnosis includes serum immunoglobulin levels, functional testing of humoral and cellular immunity, and CBC with cytoflow studies
WAS
94
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)
thrombocytopenia with absent radii syndrome (TAR)
95
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
storage pool disease or gray's platelet syndrome
96
AKA storage pool disease
gray's platelet disease
97
SPS/GPS
______ content was also decreased in the affected platelets as compared to normal
serotonin
98
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
mepacrine
99
rare and genetic
cyclooxygenase deficiency
100
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
cardiopulmonary bypass
101
Refers to deposition of large amounts of fibrin throughout the microcirculation, which results in a pathological activation of platelet aggregation and coagulation pathways
disseminated intravascular coagulation (DIC)
102
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
SLE - lupus-like anticoagulant
103
Causes platelet aggregation abnormalities because of prostacyclin production and decreased platelet TXA2 production
hemolytic-uremic syndrome
104
The most damaging metabolites to platelet function are thought to be urea, guanidinosuccinic acid, and phenolic acid
hemolytic-uremic syndrome
105
Functional inhibition is most common with the group of drugs that inhibit platelet prostaglandin production, such as aspirin
drug-induced platelet abnormalities
