Coagulation // Unit 5 Flashcards
What composes hemostasis?
vascular system
platelet
coagulation
fibrinolysis
What are the systems involved in hemostasis?
primary & secondary
What is the primary system activated by?
Small vessel damage (controls vasoconstriction/platelet function)
What is the secondary system activated by?
major trauma, surgery or hemorrhage
controls coagulation proteins & enzymatic rxns
What is coagulation?
a series of proteins that go through a series of enzymatic rxns to form fibrin
What is the life span of PLTs?
7-10 days
What is the cell that drops off PLTs at the site of injury?
megakaryocyte through endomitosis
What are the 3 phases of PLT function?
adhesion
amplification
aggregation
In the adhesion phase, what are the PLTs adhering to? What is required?
collagen, vMF & Gp1b
What makes up the vessel wall?
collagen
elastic fibers
smooth muscles
What occurs during amplification?
more PLTs are recruited to aggregate
What enforces aggregation of PLTs?
Thromboxane A2
What coagulation factor isn’t produced in the liver?
VIII
What factors make up the extrinsic pathway? Does is have a faster or slower response?
III & VII
faster
What factors make up the intrinsic pathway?
XII, XI, IX, VIII
Hemophilia A is a factor ___ deficiency?
VIII
What factor is a substrate for thrombin & a precursor of fibrin?
Factor I, fibrinogen
What factor is the fibrin stabilizing factor?
Factor XIII
What factor activates factor VII?
Factor III
Hemophilia B is a factor ____ deficiency?
IX
Deficiency of factor ___ may cause prolonged aPTT
XII
What factor accelerates the transformation of prothrombin to thrombin?
factor V
What are the contact factors?
HMWK
Pre-K
XII
XI
What pathway forms the fibrin clot?
the common pathway
What do PT & aPTT measure?
PT- extrinsic pathway
aPTT- intrinsic pathway
What type of bleeding is seen in a decreased PLT count?
gingival bleeding
epistaxis
extensive bruising
petechiae
What causes an altered distribution of platelets?
enlarged spleen
What coagulation process is vitamin K dependent?
Prothrombin group
Which drugs can cause thrombocytopenia?
quinines
NSAIDs
Sulfonamides
Diuretics
Where can closed bleeding occur?
soft tissue genitourinary gastrointestinal bleeding in muscles bleeding in bones, joints & skull
What is unique about the factor VIII molecule?
largest protein in the coagulation complex
not exclusively synthesized by the liver
forms complex w/ vMF for transportation
genetically controlled by X-chromosome
What are some symptoms of an individual with Hemophilia A & B?
bleeding in... GI tract kidneys gums muscles joints umbilical cord circumcisional hemarthrosis
What are the lab results of a person with Hemophilia A & B?
normal bleeding time
normal PT
increased APTT
How was Hemophilia A treated back in the day? What was the issue with this?
whole blood transfusion
80-90% of pts contracted HIV
What is the issue with treating Hemophilia A & B?
patients run the risk of developing inhibitors or antibodies to their infusion products
In clotting factor disorders in both bleeding and no bleeding, what are the factors?
bleeding- XIII, X, VII, V, II
no bleeding- contact activation factors (XI, XII, HMWK, Pre-K)
Describe Factor XIII clotting disorder
normal PT & PTT
tested with 5M urea test
issues/bleeding w/ pregnancy
Describe factor II, V, VII & X clotting disorders
prolonged PT & APTT
rare autosomal recessive
treated with prothrombin complex concentrates
What are causes of Vitamin K deficiency?
antibiotic therapy
nutritional deficit
biliary obstruction
malabsorption syndrome
If Vitamin K is depleted, what will show in lab results?
Increased PT & APTT
What is the role of fibrinogen in the coagulation & fibrinolytic system?
gets converted to fibrin (fibrinopeptides A & B) by thrombin and is the onset of a solid clot & is broken down by the fibrinolytic system
Name some acquired disorders of fibrinogen…
minor increases: inflammation pregnancy stress diabetes oral contraceptives
major increases:
hepatitis
atherosclerosis
decreases:
acute liver disease
acute renal disease
DIC
Name the 3 types of inherited fibrinogen disorders & their values
afibrinogenemia <10
hypofibrinogenemia 20-100
dysfibrinogenemia (qualitative)
Describe Afibrinogenemia
autosomal recessive
increased PT, PTT, TT & reptilase time
long bleeding time
abnormal PLT aggregation
Describe hypofibrinogenemia
heterozygous form of afibrinogenemia
autosomal recessive
mild spontaneous bleeding
severe postop bleeding
Describe dysfibrinogenemia
autosomal dominant
inherited homo or hetero
most lab findings are abnormal
inc PT, PTT, TT & RT
What is the role of thrombin in the coagulation system?
PLT release reaction
PLT aggregation
activation of factor V & VIII
activation of Protein C
What is the role of thrombin in the fibrinolytic system?
negative feedback by converting plasminogen to plasmin which breaks down fibrin
When is thrombin & tPA generated?
during injury to endothelial cells
What are the activators of the fibrinolytic system?
tPA factor XIIa kallikrein HMWK Urokinase
What are products or fibrinolysis called? What are their labels?
fibrin splint/degradation products X Y D E D-dimers
Which inhibitor prevents plasmin from binding to fibrin & is the most important inhibitor of the fibrinolytic system?
alpha-2 antiplasmin
What are events that can trigger DIC?
infections tissue injury malignancy heat stroke GI disorders OB complications snake bites
What may develop in patients with DIC?
microangiopathic hemolytic anemia due to microthrombi
Describe the two types of thrombosis…
arterial thrombi- PLTs. RBCs & WBCs
venous thrombi- fibrin & WBCs
What factors does antithrombin neutralize?
mostly IIa
IXa, Xa, XIa, XIIa
What are the inherited risk factors for thrombosis?
AT deficiency Protein C deficiency Protein S deficiency Factor V Lieden Prothrombin Mutation
What are the two forms of protein S & their %’s?
free 40%
C4b bound 60%
What are the differences between the two types of type II qualitative protein S disorders?
IIa - reduced free protein with normal total protein
IIb - both free & total protein are normal
What are the most common acquired risk factors for thrombosis?
LA/Antiphospholipid syndrome
HIT
What are the specimen requirements for coagulation testing?
3.2% sodium citrate
9:1 dilution
spin @ 3000 rpm for 5 min
Hct >60% need to be drawn differently
Which drug inhibits the formation of thromboxane A2?
aspirin, antiplatelet drug
What is special about coumadin?
long term anticoagulant
inhibits vitamin K dependent coagulation factors (II, VII, IX, X)
