2.4 and 2.5 Platelets Flashcards
Platelets adhere to _______________, which is mediated by ____________
subendothelial collagen; vWF
Platelet dense granules contain
ADP
Platelet alpha granules contain (5)
β-thromboglobulin; platelet factor 4; PDGF; fibrinogen; factor V
Platelet lysozymes contain
hydrolase
To quantify platelets, you should collect blood into what type of tube
purple top (EDTA)
When it comes to MPV, there is an inverse relationship between ______ and _______
size and number (more platelets but smaller size vs less platelets but larger size)
what can artifacturally lower platelet counts in an analyzer
platelet clumping
shift platelets indicate
increased thrombopoiesis
small platelets can be a sign of
iron deficiency; ITP
platelet concentration changes due to (3)
decreased thrombopoiesis; increased destruction of platelets; increased consumption of platelets
what can be used to assess platelet function/number
BMBT
when would you NOT do a BMBT test
if the patient has thrombocytopenia
BMBT is _____________ with coagulation factor deficiencies
unaltered
if you wanted to assess the entire clotting mechanism, what test would you use
thromboelastography
T/F petechial hemorrhages are characteristic of Von Willebrands Disease
F
what are the clinical signs of von willebrands disease
1) bleeding from mucous membranes
2) prolonged bleeding after trauma, surgery, venipuncture
vWF allows platelet adhesion to_____________, _________________ and stabilizes
subendothelium, platelet-platelet adhesion, FVIII
_______ is an example of thrombocytopenia due to destruction and causes (marked/moderate) thrombocytopenia
ITP; marked
______ is an example of thrombocytopenia due to consumption and causes (marked/moderate) thrombocytopenia
DIC; moderate
most of the pro-coagulation factors are made in the _________ and are ________
liver; enzymes
what are the vitamin K dependent factors
2, 7, 9, 10
what are the contact factors
11, 12, 13, prekallikrein
what are the non-enzymatic factors
5, 8, fibrinogen
what are the three anti-coagulant factors
antithrombin III; protein C; tissue factor pathway inhibitor
the main protein responsible for degrading fibrin is
plasmin
the intrinsic pathway is also called the
contact pathway
the extrinsic pathway is also called the
tissue factor pathway
in vivo, which pathway is activated first
extrinsic
activation of coagulation occurs on the surface of _________, which have a ________ charge
platelets; negative
what is the role of calcium in the coagulation cascade
provides the positive charge between the negatively charged platelet membrane and negatively charged coagulation factors
which tests require citrated tubes
APTT, OSPT, fibrinogen
ACT tests which pathways
intrinsic and common
what is an important consideration before running ACT
need to do a CBC first to make sure patient does not have thrombocytopenia, because the test relies on the patients own platelets
what is an advantage of ACT
inexpensive and easy to do in practice
APTT (PTT) tests which pathways
common and intrinsic
what is an advantage of APTT
is not affected by thrombocytopenia
with clotting factor disorders, we tend to see ________, whereas with platelet disorders, we tend to see __________
hematomas; petechiae
hemophilia A is a deficiency of
Factor VIII
OSPT tests which pathways
extrinsic and common
APTT tests which 5 diseases
hemophilias; DIC; hereditary factor XII or XI deficiency; vitamin K deficiency; therapeautic anticoagulation
OSPT tests which 3 diseases
factor VII deficiency; DIC; vitamin K deficiency
what is an advantage of OSPT
not affected by thrombocytopenia
which test is inversely proportional to TCT
fibrinogen
fibrinogen tests for what 3 disorders
hereditary hypo or dysfibrinogenemia; DIC; therapeutic anticoagulation
elevated FDPs can indicate which diseases (3)
DIC; renal disease; internal hemorrhage
DIC is diagnosed by _____ OSPT and APTT; _____ FDPs; ____ fibrinogen; _______ platelets and ____________________
increased; increased; decreased; decreased; RBC fragmentation
what is an RBC abnormality seen in DIC
shistocytes
what are some causes of hypercoagulability
DIC
hypoalbuminemia
loss of antithrombin III
polycythemia
hyperviscosity, proteins/cells
shock
drugs, platelet agonists
snake bites, other toxins
what can cause thrombocytosis
1) splenic contraction
2) iron deficiency
3) hemorrhage
4) paraneoplasia
5) myeloproliferative disease
6) FelV associated disease (non-neoplasia)
7) inflammatory disease
