Thrombosis & DIC Flashcards
What are physiologic coagulation control methods?
blood flow-wash away activated factors
natural anticoagulant processing
-antithrombin inactivates enzymes thrombin & Xa
-protein C digests cofactors V & VIII
What makes up Virchow’s triad?
endothelial injury *
abnormal blood flow
hypercoagulability
Is antithrombin or protein C system vitamin K dependent?
protein C/S system
Which type of thrombosis are primary hypercoagulable states associated with?
venous
What are the 3 types of primary hypercoagulable states?
deficiency of control proteins (AT, PC, PS)
subtle changes causing control mechanisms (leiden V)
increased coagulation factor levels (prothrombin gene variation G20210A)
When does the risk of thrombosis in AT/PC/PS deficiencies increase?
after puberty
How do you test for AT, PC/PS deficiencies?
functional AT, PS or PS assay
protein S free antigen
What happpens to PTT in a patient with resistance to activated protein C?
failture of PTT to prolong in response to addition of activated protein C
If PTT fails to prolong in response to addition of activated protein C what test do you perform next?
genetic defect of factor V test (gain of function mutation)
(factor V leiden: Arg 506 replaced wtih Gln
What are the key features of leidein factor V?
venous throbosis risk factor
causes DVT
common in caucasians
What are the key features of prothrombin gene variation?
G20210A mutation, leads to higher levels of transcription
associated with venous events DVT/PE
via elevated thrombin levels
(more freq than def of AT, PC, PS)
risk of venous thrombotic event similar to leiden factor V, weaker than AT/PC/PS
What is antiphospholipid antibody syndrome?
Key lab findings?
Symptoms?
venous &/or arterial thrombosis
recurrent fetal wastage/preg loss
evidence of antiphospholipid antibody/lupus like anticoag/positive antiphospholipid serology
may have thrombocytopenia
What is the mechanism of antiphospholipid antibody syndrome as understood to date?
auto-antibody to phospholipid-protein complex
-anti-cardiolipin/lupus antigoaculents present
inhibits phospholipid depenant in vitro coag assays
-inhibitor: failure to clot time to correct on 1:1 mix
-phospholipid dependence: clot time corrects with high PL
can cause false positive syphillis serology
Features of “lupus-like” anticoagulant
inhibitor of phospholipid dependent in vitro assays of coagulation
- prolonged PL dependent clot time (dRVVT or PTT)
- failture of correction on 1:1 mix study
- correction occurs in lipid rich assay
What causes both arterial and venous thrombosis?
homocysteine
apla syndrome
What are acquired risk factors of thrombosis?
obstruction to flow (pregnancy) activation of hemostatic mechanism (spesis, neoplasm, foregin body) damaged endothelium (infl, atherosclerosis, trauma, etc)
What are risk factors for secondary hypercoagulable states?
post op
neoplasm
immobilizaiton
What is DIC?
widespread acivation of thrombin nad plasmin mechanisms
- overwhelmed control mechanisms
- consumption of participants in hemostasis
- pay present as bleeding or thrombosis
What are syndromes associated with DIC?
intro of extrinsic clot promoting material intravascular elaboration of procoagulants vascular injury (ie/sepsis)
What is purpura fulminans?
presenting symptom of DIC caused by meningococcal spesis or severe protein C deficiency in a newborn
Clinical presentation of DIC?
bleeding from venipunctures and other sites
purpura fulminans
What is the screening test for DIC?
D-dimer
Lab values for DIC
prolonged PT/PTT
decreased fibrinogen
low platelets
D-dimer elevated
What are the consequences fo DIC?
microcirculatory failure leading to multiorgan dysfunction
