Clotting GK Flashcards
Platelets and clotting factors circulate normally in an _________ form.
Platelets and clotting factors circulate normally in an inactive form.
Vascular injury disrupts endothelium and leads to what 3 things?
- Vascular spasm
- Platelet adhesion mediated by Von Willebrand factor
- Coagulation cascade
What does PT represent?
time in seconds for plasma to clot after addition of calcium and an activator of extrinsic pathway (thromboplastin)
What leads to a prolonged PT?
Deficiencies or inhibitors of clotting factors within extrinsic or final common pathways
Why was INR created?
PT results for identical patients vary with different labs
What is INR?
mathematical conversion of patient’s PT compared to geometric mean of PT of at least 20 healthy subjects of males and females at THAT lab
What does PTT (Partial Thromboplastin Time) measure?
integrity of intrinsic and final common pathways of coag cascade
What does PTT represent?
time in seconds for patient’s plasma to clot after the addition of phospholipid, an intrinsic pathway activator- calcium
if clotting times remain prolonged what should you think?
inhibitor
if clotting times normalize or decrease to near-normal what should you think?
factor-deficiency
What does PTT correct?
Factor DEFICIENCY of intrinsic pathway like factors VIII, IX, XI, or XII
How can you determine which clotting factor is involved with an abnormal PTT?
clotting factor assay
PTT stays prolonged with what?
an inhibitor: heparin, LMWH, AIH/Factor 8 inhibitor
Lupus anticoagulant
What do you see in pts w/LAC (lupus anticoag)?prolonged PTT
prolonged baseline PTT
Seen more in young females
When would you suspect LAC?
pt w/no bleeding hx
pt w/clot w/baseline prolonged PTT before Ant-coag was started
What should you think if a PT corrects with normal PTT?
DEFICIENCY of factors II, VII, and X or fibrinogen (2, 7, 10)
Liver dz (prolonged PT)
What should you think if PT is still prolonged with prolonged PTT?
Factor 5 inhibitor
PT and PTT MIxing study:
deficiencies caused by what?
supratherapeutic warfarin or rat poison
what inhibitors will you see in lymphoproliferative d/o or monoclonal protein d/o?
LAC
nonspecific factor inhibitors
Pts with what 2 disorders can develop antibodies against self (have autoimmune characteristics)?
lymphoproliferative d/o
monoclonal protein d/o
Warfarin:
What can supratherapeutic INR lead to?
elevated PTT
every 1.0 increase of PT is what of PTT?
16-17 sec PTT
3 MC reasons to use Warfarin
1) A-Fib INR 2-3
2) VTE INR 2-3
3) Mechanical valve replacement- INR 2.5-3.5
Warfarin interferes with what factors and proteins?
factors VII, IX, X and proteins C & S
Can you use warfarin in pregnancy?
No: Preggo X
UFH inhibits which factors?
IIa (thrombin)
Xa
UFH PK and risk
PK: large molecule: 30 units long and not well absorbed subcutaneously
risk of HIT
What does LMWH inhibit?
More of Xa
some of IIa
LMWH benefits
smaller so well absorbed subcutaneously
predictable 1/2 life
Ex: Enoxaparin, Dalteparin
Risk of HIT
Can give with preggos
T/F: No need to draw blood tests to see if anticoag is therapeutic unless pt. is very obese or very thin
What would you draw if you had to?
TRUE
anti-factor Xa levels 3-4 hrs post LMWH administered
synthetic pentasaccharide that inhibits factor Xa and binds to antithrombin III causing antithrombin III to go through conformational change inhibiting coag cascade
Half-life 17 hrs. long and NO reversal agent
Which med?
Fondaparinux
Direct Xa inhibitors
Rivaroxaban
Apixaban
ex of DOAC
dabigatran
what are fondaparinux, rivaroxaban/apixaban and dabigatran used for?
A-fib & VTE
What agents should be used to reverse overdose in the following meds?
- Heparin
- Enoxaparin
- Pradaxa
- Xarelto
- Fondaparinux
- Heparin: Protamine
- Lovenox/Fragmin: Protamine
- Pradaxa: Dialysis (if bleeding in brain) or Idarucizumab (if no bleeding)
- Xarelto/Eliquis- PCC
- Fondaparinux (Arixtra)- Novo 7, DDAVP
RF for VTE & hypercoagulable state
stasis
recent trauma/surgery and hypercoagulable state
increased risk for venous thromboembolism (VTE)
CA (Trousseau’s syndrome)
pregnancy
smoking
estrogen
Protein C & S along with antithrombin III deficiencies
Factor V Leiden mutation
Prothrombin gene mutation
Lupus anticoagulant
Hyperhomocysteinemia
Anticardiolipin antibody
Paroxysmal nocturnal hemoglobinuria
These are all…
hypercoagulable states
what 3 things prevent overclotting?
Protein C, Protein S, and Antithrombin III
Both are vitamin K dependent proteins
Both can be low in nephrotic syndrome
Protein C &S
Can be low d/t liver disease, nephropathy or heparin
Mutations reduce levels or decrease its functional capacity
Antithrombin III deficiency
