Coagulation Flashcards
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?
Vasoconstriction
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?
Sodium citrate
Prothrombin time measures what pathway?
Extrinsic to common
What 3 things can cause PT increase?
- VII deficiency or deficiency in other factors or inhibitors to them
- Vitamin K deficiency from liver disease, warfarin, or antibiotics
- Liver disease
- 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?
- DIC
- Thrombosis
- End stage liver disease
- 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?
6 months
Factor VIII
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