ABSITE Review - Hematology Flashcards
What are the three initial responses to vascular injury?
Vascular vasoconstriction, Platelet adhesion, Thrombin generation
What is the convergence point betweem the intrinsic and extrinsic pathway?
Factor X
Which coagulation factor helps with fibrin crosslinking?
Factor XIII
What are the functions of thrombin?
Key to coagulation
Converts fibrinogen to fibrin and fibrin split products
Activates factors V and VIII
Activates platelets
What are the functions of antithrombin III?
Key to anticoagulation
Binds and inhibits thrombin
Inhibits factors IX, X, XI
Heparin binds AT-III
What are the functions of protein C?
Degrades factors V and VIII
Degrades fibrinogen
What is the function of tissue plasminogen activator?
It is released from the endothelium and converts plasminogen to plasmin
What is the function of plasmin?
Degrades factors V, VIII, fibrinogen and fibrin –> lose platelet plug
What coagulation factor has the shortest half life?
Factor VII
Which are the labile coagulation factors?
Factors V and VIII, activity is lost in stored blood but not in FFP
Which is the only factor not synthesize in the liver?
Factor VIII which is synthesized in the endothelium
Name the vitamin K-dependent factors.
II, VII, IX, X, protein C and protein S
How long it takes to witamin K to take effect?
6 hours
How long FFP lasts?
Effect is immediate and lasts 6 hours
Describe the half-life of RBCs, PLTs, PMNs.
RBCs 120 days
PLTs 7 days
PMNs 1-2 days
Where protacyclin is produce and what is its function?
Comes from endothelium.
Decreases platelet aggregation and promotes vasodilation.
Where thromboxane is produce and what is its function?
Comes from platelets.
Increase platelets aggregation and promotes vasoconstriction.
Triggers release of calcium in platelets –> exposes GpIIB/IIIa receptor and causes PLT to PLT binding, PLT to collagen binding
What coagulation factors are present in cryoprecipitate?
Contains the highest concentration of vWF VIII and fibrinogen
What coagulation factors are present in FFP?
High levels of all factors, protein C, protein S and AT-III
What cause release of VIII and vWF from endothelium?
DDAVP and conjugated estrogens
What PT measures?
Measures II, V, VII and X; fibrinogen; best for liver synthetic function
What PTT measures?
Measures most factors except VII and XIII; fibrinogen
What is ACT and what arange is needed for anticoagulation?
Activated clotting time
ACT 150-200s for routine anticoagulation
ACT 460s for CABG
What is the MC congenital bleeding disorder?
von Willebrand’s disease
What is the function of vWF?
Links GpIb receptor on PLTs to collagen
What are the diagnostic lab findings on vWF disease?
Normal PT
Normal or abnormal PTT
Long bleeding time (ristocetin test)
What is the most common and/or severe type of vWF disease?
MC type - Type I (autosomal dominant)
Most severe type - Type III (autosomal recessive)
Describe the genetics and diagnostic lab findings for Hemophilia A.
VIII deficiency Sex-linked recessive Need levels 100% preop and keep at 30% after surgery Dx - Prolonged PTT and normal PT Factor VIII crosses placenta
Describe the genetics, diagnostic lab findings and treatment for Hemophilia B.
IX deficiency Sex-linked recessive Need levels 100% preop Dx - Prolonged PTT and normal PT Factor VIII crosses placenta Tx - recombinant factor IX concentrate or FFP
Mention the diagnostic lab findings and treatment for Factor VII deficiency.
Dx - Prolonged PT, normal PTT, bleeding tendency
Tx - recombinant factor VII concentrate, FFP
What medications can cause Acquired thrombocytopenia?
H2 blockers, heparin
What is the defect in Glanzmann’s thrombocytopenia and treatment?
GIIb/IIIa receptor deficiency on platelets
Tx - platelets
What is the defect in Bernard Soulier thrombocytopenia and treatment?
GpIb receptor deficiency on platelets
Tx - platelets
What is the MOA of Ticlopidine?
Decreases ADP in platelets, prevent exposure of GpIIb/IIIa
What is the MOA of Dipirydamole?
Inhibits cAMP PDE, increases cAMP, decreases ADP-induced PLT aggregation
What is the MOA of Pentoxifylline?
Inhibits PLT aggregation
What is the MOA of Clopidogrel (Plavix)?
ADP receptor antagonist
How ticlopidine, dipirydamole, pentoxyfylline and Plavix thrombocytopenia is treated?
PLTs
Mention the cause of HIT.
AntiPLT antibodies (IgG PF4 antibody)
What two MC findings in patients with HIT?
Thrombocytopenia (decrease of 50% PLTs or below 100) and thrombosis (white clot)
What is the treatment for HIT?
Stop heparin
Give argatroban, hirudin, ancrod or dextran to anticoagulate
What are the lab findings of DIC?
Decrease PLTs, prolonged PT, prolonged PTT, low fibrinogen, high fibrin split products, high D-dimer
What is the MOA of ASA and how long before surgery it need to be stop?
Inhibits COX in PLTs
Stop 7 days prior to surgery, pts will have prolonged bleeding time
What PLT level is adequate before and after surgery?
Keep > 50,000 before surgery and > 20,000 after surgery
When urokinase is release and what is the MOA and treatment?
Can be release during prostate surgery and activates plasminogen causing thrombolysis
Tx- aminocaproic acid
What is the MC congenital hypercoagulability disorder? What is the defect and treatment?
Leiden factor - 30% spontaneous venous thromboses
Resistance to activated protein C, defect on factor V
Tx - heparin, warfarin
What is the treatment for Hyperhomocysteinemia?
Folic acid and B12
What is the treatment for AT-III deficiency?
Recombinant AT-III concentrate or FFP followed by heparin or hirudin or ancrod; warfarin
What parameters are needed prior to surgery on a patient with polycythemia vera?
Keep Hct < 48 and PLTs < 400 before surgery
Mention how to diagnose and treat Lupus anticoagulant.
Dx- prolonged PTT (but hypercoagulable and does not correct with FFP), positive Russell viper venom time, false-positive RPR test for syphilis
Tx - heparin, warfarin
Mention some causes of acquired hypercoagulability.
tobacco (MC), malignancy, infammatory states IBD, infections, OCP, pregnancy, RA, postop pts, myeloproliferative disorders
What is the etiology of warfarin-induced skin necrosis?
Occurs when pt receives coumadin without being heparinized first. Protein C and S has a short half life and are the first to decrease compare with the procoagulatyion factors.
What is the Virchow’s triad?
Stasis, endothelial injury and hypercoagulability
What is the treatment for 1st, 2nd and 3rd DVT or PE?
1st - warfarin for 6 months
2nd - warfarin for 1 year
3rd or significant PE - warfarin for lifetime
Where is the MC place for DVT and why?
LLE due to compression of L common iliac vein by arterial system.
What are the indications for a IVC filter?
- Patients with contraindication to anticoagulation
- Documented PE while on anticoagulation
- Patients with free-flating iliofemoral, IVC or femoral DVT
- Patients s/p pulmonary embolectomy
Most PEs come from ____________ region.
Iliofemoral
What is the MOA of warfarin?
Prevents vitamin K-dependent decarboxylation of glutamic residues
What is the MOA of SCDs?
Improve venous return but also induce fibrinolysis with compression (release of tPA).
What is the MOA of heparin? How can it can be reversed?
Activates AT-III
Reversed with protamine (1-1.5mg/100U heparin)
What is the half-life of heparin? Where heparin is proccesed?
60-90 minutes
Cleared by Reticuloendothelial system
What is the MOA of hirudin?
Irreversible direct thrombin inhibitor - the most potent
What is the MOA of argatroban?
Direct thrombin inhibitor, half life 50 minutes
What is the MOA of bivalirudin (Angiomax)?
Reversible direct thrombin inhibitor, half life 25-30 minutes
What is the protamine reaction?
Hypotension, bradycardia and decreased heart function
What is the MOA of aminocaproic acid?
Inhibits fibrinolysis by inhibiting plasmin
What are the ABSOLUTE contraindications to thrombolytic use?
Active internal bleeding; recent CVA (<2 months); Intracranial pathology
What are the MAJOR contraindications to thrombolytic use?
Recent (<10 days), organ biopsy, or obstetric delivery; L heart thrombus; active peptic ulcer or GI abnormality; recent trauma; uncontrolled HTN
What are the MINOR contraindications to thrombolytic use?
Minor surgery; recent CPR; Afib w MV disease; bacterial endocarditis; hemostatic defects; diabetic hemorrhagic retinopathy; pregnancy