Pathophysiology of Coagulopathy Flashcards
What differences in solubility exist between fibrin and fibrinogen?
Fibrinogen - soluble
Fibin - not soluble
What products are created from fibrinogen cleavage by plasmin?
Fibrin monomer
Fibrinopeptide A
Fibrinopeptide B
Why does a fibrin polymer by itself not last very long?
Fibrin polymers are only bound through hydrogen bonding and so are transient in the fast moving blood
**Typically only lasts about 24 hours
What clotting factor is primarily responsible for prolonging the life of a fibrin clot?
• how so?
XIII, it creates COVALENT crosslinks between fibrin polymers
What would happen if you cut someone who had a factor 13 deficiency?
They would clot then re-bleed
What does the prothrombolytic complex consist of?
Factor Xa (enzyme) Factor V (cofactor) Ca2+
When you need to perform clotting assays should you use plasma or serum?
Plasma, serum lacks clotting factors because blood has been allowed to clot
If you have a prolonged PT only, what factors may be messed up?
PT - EXTRINSIC pathway measurement
• Factor VII
**Tissue Factor really isn’t measured because its part of the reagent that is added to perform the test
If you have a prolonged PT and PTT what factors may be messed up?
PTT and PT - INTRINSIC and EXTRINSIC measurement
• If both are messed up it must be in a pathway common to both - COMMON PATH
- Factor II
- Factor V
- Factor X
If you have a prolonged PTT only, what factors may be messed up?
PTT - INTRINSIC pathway measured
- Factor XII
- Factor XI
- Factor VIII
- Factor IX
Suppose you have a clotting factor that is severely mutated but PT and PTT are normal, what factor is this likely to be?
Factor XIII, is needed for crosslinking only but lack of XIII will not hinder initial clot formation
Suppose you have a clot, then at 5M urea and it returns to blood. What is a likely cause?
Factor XIII deficiency, clot returns to blood because Urea disrupts normal hydrogen bonding in the clot
What are the proenzymes in the coagulation cascade?
• Cofactors?
Proenzyme:
• II, VII, IX, X, IX ***Note: 1st four are all vit. K dep.
Cofactor:
• Tissue Factor, Factor VIII, factor V
T or F: people who take warfarin have fewer clotting factors.
False, people who take Warfarin have the same amount of clotting factors, they just aren’t active because they aren’t gamma carboxylated
Why is measurement of D-dimers important?
It is something that could ONLY show up in fibrin that has been previously polymerized
DON’T MAKE Dx. ON THE BASIS OF D-DIMERS
Where is thombomodulin found?
• What does it do?
- Thrombomodulin - found on surface of normal epithelial cells
- Activates protein C after combining with thrombin
T or F: antithrombin acts on all serine proteases except for VIII.
False, VIII is not a serine protease.
• It acts on all serine proteases (II, IX, X) except VII.
What should be the 1st and 2nd things in your differential diagnosis of thombocytopenia in adults?
- COULD IT BE LAB ARTIFACT?
2. Malignancies, Sequestration, Consumption
What physical sign suggests sequestration of platelets?
• Big Spleen
***What triad should make you think TTP?
- Fluctuating Neurological Symtoms
- Unexplained Fever
- Thrombocytopenia
**These are all very random when separate but should stand out to you when you see them together
What should you do if you see the TTP triad of:
• Fluctuating Neurological Symptoms
• Unexplained Fever
• Thrombocytopenia
Peripheral blood smear to check for Schistocytes
**If you see them, start treating for TTP and run tests to do a differential between TTP, HUS, and aHUS
Look up ITP (immune thrombocytopenia purpura) if you don’t talk about it in class tomorrow
Look up ITP (immune thrombocytopenia purpura) if you don’t talk about it in class tomorrow
