Flashcards in Coagulation Deck (70):
What are the 3 constituents of the hemostatic system?
Coagulation proteins, endothelium, platelets
What is the purpose of the coagulation system
Thrombin formation leading to a fibrin clot
What is the purpose of the fibrinolytic system?
To lyse the clot
What is the purpose of the anticoagulant system?
Regulate all the enzymes so neither the coagulation or fibrinolytic system occurs in excess
What is the first stage of coagulation?
In the first stage of coagulation, what causes vasoconstriction?
Reflexes and endothelin release from the site of injury
What is the second stage of coagulation?
Primary hemostasis where platelets aggregate
In the second stage of coagulation, how do platelets attach to collagen?
Via von willebrand factor
What substances are released from platelet granules and what does this cause?
ADP and TXA2 leading to further recruitment of platelets and the formation of a hemostatic plug
What is the 3rd stage of coagulation?
Secondary hemostasis or fibrin formation
What is released in the third stage of coagulation and what affect does it have?
Tissue factor, leads to thrombin activation. A plug is formed and WBC and RBCs are trapped
The 4th stage of coagulation is?
Crosslinking of fibrin and fibrinolysis
What two substances are released in the tertiary stage and what do they do?
t-PA for fibrinolysis
Thrombomodulin which blocks the coagulation cascade
Which factors are vitamin K dependent?
2,7,9,10, S, C
What testing good specimens what is used as an anticoagulant?
Prothrombin time measures what pathway?
Extrinsic to common
What 3 things can cause PT increase?
1. VII deficiency or deficiency in other factors or inhibitors to them
2. Vitamin K deficiency from liver disease, warfarin, or antibiotics
3. Liver disease
4. Deficiencies in common factor 1,2,5,10
aPTT measures what pathway?
Intrinsic to common
What is the heparin effect?
Increased aPTT time due to use of this injectable anticoagulant
What can cause factor deficiency or inhibitor?
Hemophilias A, B, and C and amyloid disorder
The thrombin time test is for?
Fibrin generation test, fibrinogen or factor 1
D-dimer is an indication of?
Fibrin has been formed and degraded
D-dimer and FDP are elevated in what conditions, what type of cancer?
3. End stage liver disease
4. Mucin-secreting adenocarcinomas
In a mixing study, if clotting times are prolonged this means?
An inhibitor is present
In a mixing study, if clotting times decrease this means?
There is a factor deficiency
When do factors in neonates reach adult levels? Which factor is typically present at a similar level?
How is hemorrhagic telangiectasia inherited? What does it cause?
Autosomal dominant, leads to abnormal blood vessel formation in the skin and organs. Leads to nosebleed and bleeding of the GI tract and other organs
How do you treat hemorrhagic telangiectasia?
Avoid bleeding as much as possible and supplement iron
What is Elhers-Danlos syndrome?
A group of inherited CT disorders caused by defects in collagen I and III synthesis
Patients with Elhers-Danlos have what symptoms?
Thin skin that is pale and you can see their veins, bruise very easily
What are the four acquired coagulation protein defects?
1. Factor X deficiency
2. Vitamin K deficiency
4. Liver disease
What factor is deficient in the 3 hemophilias?
A is factor 8
B is 9
C is 11
What is the severity of most hemophiliacs?
What can cause bleeding in those with mild hemophilia?
Surgery or major trauma
Female carriers of hemophilia often have factor VIII activity in what range?
Greater than 50% so normal
Lab tests on carriers will show?
Normal PTT but increased vWF to factor VIII ratio, 2:1 as opposed to 1:1
What can cause the presence of factor VIII inhibitors in non-hemophiliacs?
Idiopathic conditions, SLE or rheumatoid arthritis, lymphomas and solid tumors, drug reactions, pregnancy and postpartum state
How is hemophilia C inherited?
Hemophilia C causes bleeding of what severity?
Disseminated intravascular coagulation is caused by?
Numerous microvascular clots due to a substance that behaves similar to tissue factor.
Disseminated intravascular coagulation leads to?
What are causes of disseminated intravascular coagulation?
Snake venom, infections, obstetric complications, mucin-secreting adenocarcinomas
What 4 things are decreased in DIC?
Platelet count, factor assay, fibrinogen, and antithrombin
Thrombophilia is characterized by?
Hypercoagulability and an increased propensity for thrombosis
What is the most common cause of acquired thrombophilia?
What are the two common clinical features of inherited thrombophilia?
Deep vein thrombosis of lower limbs, pulmonary embolism
What two rare clinical features are characteristic of inherited thrombophilia?
Mesenteric vein thrombosis and cerebral vein thrombosis
Protein C deficiency is inherited by?
The initial thromboembolic episode occurs normally or spontaneously?
Protein C deficiency usually affects what veins?
Deep veins of the leg, ileofemoral veins, and mesenteric veins
Describe the 2 types of protein C deficiency?
Type 1 there is decreased protein C
Type 2 there is decreased functionality of protein C
How does homozygous protein C deficiency present itself in newborns?
What is protein S?
An essential cofactor of protein C
How does protein S circulate?
Freely or complex to c4b binding protein
What is the most common hereditary thrombophilia?
APC resistance or activated protein C
How is APC resistance inherited?
APC resistance is associated with a mutation in what gene>
Factor V gene, substitute arginine for glutamine
What is the reference range for INR?
What level INR indicates a high chance of bleeding? High chance of clot? What is the target range for anticoagulant use?
5, 0.5, 2-3
Increased thrombin time if associated with what congenital disorders?
Afibrinogemia and hypofibrinogemia
Results of factor activity tests for normal adults fall between?
In those with factor VIII inhibitor a mixing study will show?
Immediate correction of pTT that prolongs after 1 hour
Hemophilia C is a deficiency in? What is the result?
Factor XI, results in mild bleeding
What causes inherited afibrinogenemia and hypo?
Autosomal recessive mutations that truncate the protein
What is associated with afribogenemia?
Prolonged pt and ptt and bleeding disorder similar to moderate to severe hemophilia A
What is the first manifestation of inherited hypo or afibrinogenemia?
Umbilical cord hemorrhage then life long bleeding diasthesis
Factor 13 deficiency will result in? Blood test will show?
Mild delayed bleeding, normal Pt, ptt, and tt
Amyloidosis will result in decreased?
Vitamin K deficiency results in decreased?