Coagulation Flashcards
What level of the vessel has the tissue factor?
It is in the adventitia (connective tissue)
If the adventitia is exposed, something bad has happened
Which vessels are more likely to have damage?
Which vessels clot better?
arteries have more damage d/t fast flow
veins clot better d/t slow flow
What does Von Willebrand factor do?
- Nothing until it comes in contact with collagen
- Then it acts like a bridge between the collagen and the glycoprotein Ib platelet receptor
- this receptor sticks the platelet to the von willebrand factor
- Once bound to von Willebrand factor the platelets will expose their GpIIb-IIIa receptors which will bind to fibrinogen and bind platelets together
What is D-dimer indicative of?
clot breakdown
What is Hemophilia A?
- Factor 8 deficiency
- X-linked
- Factor 8 must be <1% of normal to have severe bleeding
- Prolonged PTT
- PT is normal
- These patients will still have extrinsic pathway, but without Factor 8a or 9a (deficient in hemophilia B), they cannot have “explosive” activation of 10a
- external cuts on skin are no problem b/c they have extrinsic pathway
- internal bleeding, like in joints are problematic
- cause arthritis
How is Hemophilia B different from Hemophilia A?
- Hemophilia B is Factor 9 deficient
Factor XI deficienty
genetics:
who has it?
diagnosed it what lab?
- Autosomal recessive
- affects about 5% of Ashkenazi Jews
- Prolonged PTT
- generally mild
What does Factor XIII deficiency cause?
How is it diagnosed?
- Factor 13 deficiency prevents the crossbridges of fibrinogen from being built. This makes the clots weak
- PT and PTT both measure the clotting cascade from 12 down to 1, but 13 is the last step and problems with it are not picked up on these labs
- very difficult to diagnose
Von Willebrand disease
gentetics
types
- Autosomal dominant or autosomal recessive
- Can either be no vWF, which is the most life threatening form but is very rare
- Or they can have vWF, but it doesnt work as well
- form clots, just slower than normal
What are Acquired factor 8 or 9 inhibitors?
- acquired disease that looks like Hemophilia 8 or 9, but instead of not having the factors, they are getting destroyed
- Cannot treat by giving them ffp or factors because the transfused factors will just be ruined as well
What are some congenital disorders that result in low platelets?
-
Congenital hypoplastic thrombocytopenia with absent radii
- autosomal recessive, missing radius
-
Fanconi anemia
- autosomal recessive
- congenital aplastic anemia with severe pancytopenia
- often progresses to acute leukemia
-
May-Hegglin anomoly
- ineffective platelet production
- thrombocytopenia with giant platelets
-
Wiskott-Aldrich syndrome
- X-linked
- presents with eczema, immunodeficiency, and throbocytopenia
What are acquired issues that result in defective platelet production?
- bone marrow damage
- aplastic anemia, myelofibrosis, or leukemia with pancytopenia
- Vitamin B12 or folate deficiency
- DNA synthesis needed for megakaryocyte production
What characterizes Thrombotic thrombocytopenic purpura (TTP)?
What causes it?
What are the 5 signs?
- Characterized by formation of platelet-rich thrombi in the arterial and capillary microvasculature
- Deficiency of ADAMTS13 protease
- usually this protease cuts ultra large vWF ultimers into smaller pieces
- without it, they become too big, making throbus and using up all the platelets
- Five signs of TTP:
- fever
- renal failure
- thrombocytopenia
- microangiopathic hemolytic anemia
- neurologic abnormalities
- TTP is an emergency!
What is hemolytic uremic syndrome (HUS)?
- Typically seen in children with bloody diarrhea due to infection with a particular strain of E.coli that produces a shiga-like toxin
- Toxin causes coagulation to occur, traps RBCs
- RBCs then get chopped up and chunks get caught in the basement membrane of the kidney
- this causes renal failure
What is HELLP syndrome?
- Combination of RBC hemolysis (H), elevated liver enzyme levels (EL), and low platelet count (LP)
- Thrombocytopenia is a frequent complication of pregnancy
What is DIC?
- Some kind of trauma causes LOTS of tissue factor to be released
- clotting starts hapening everywhere, leading to ischemia
- Plasmin is activated to break down the clots
- this leeds to bleeding
- simultaneously bleeding and clotting (microvascular thrombus) makes it VERY difficult to treat
What is Virchow’s triad?
- Endothelium integrity is the most important factor
- injury can alter blood flow and affect coagulability
- Abnormal blood flows (stasis or turbulance) can cause endothelial injury
