1. Thrombophilia (Hypercoagulable States)
Abdulkareem Almomen, MD
Professor of Medicine & Hematology,
King Saud University
MED 341, Feb.2014

2. Risk factors for thrombosis
Acquired
thrombophilia
Hereditary
thrombophilia
Atherosclerosis
Thrombosis
Surgery
trauma
Immobility
Estrogens
Inflammation
Malignancy

3. High-molecular-weight kininogen
Tissue factor pathway inhibitor
Form endothelium and inhibit coagulation
thrombin activatable fibrinolysis inhibitor: which modifies fibrin to make it more resistant to the tPA-mediated plasminogen.

4. Thrombomodulin-thrombin complex increase the speed of activation of protein c thus activate VIII and also Thrombomodulin-thrombin complex activate TAFI to inhibit fibrinogen and tBA thus inhibit fibrinolysis
Thrombomodulin by itself activate thrombin and coagulation
Protien S works as a cofactor for Protein C to inactivate factor VIII and V
Tissue factor pathway inhibitor inhibit factor X and VII

5. Risk Factors for Venous Thrombosis
Inherited
Acquired
Mixed/unknown

6. Risk Factors—Inherited
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
Factor V Leiden mutation (Factor V-Arg506Gln)
Prothrombin gene mutation (G A transition at position 20210)
Hyperhomocysteinemia

7. Risk Factors—Acquired
Antiphospholipid antibody syndrome
Myeloproliferative Disorders
Heparin-induced thrombocytopenia (HIT)
Prolonged air travel
Advancing age
Prior Thrombosis
Immobilization
Major surgery
Malignancy
Estrogens

8. Risk Factors—Mixed/Unknown
Hyperhomocysteinemia
High levels of factor VIII (8)
Acquired Protein C resistance in the absence of Factor V Leiden
High levels of Factor IX, XI (9,11)

9. Predictors of Thrombosis and Relative Risk
Thrombophilic Factor Relative Risk
Antithrombin deficiency – 10
Protein C deficiency 7 – 10
Protein S deficiency 8 – 10
Factor V Leiden/APC resistance 3 – 7
Prothrombin A mutation
Elevated Factor VIII 2 – 11
Lupus Anticoagulant
Anticardiolipin antibodies
Mild Hyperhomocysteinemia

10. Site of Thrombosis vs. Risk Factor
Abnormality Arterial Venous
Factor V Leiden
Prothrombin G20210A
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
Hyperhomocysteinemia
Lupus Anticoagulant

11. Other Predictors for Recurrent VTE
Venous thromboembolism
Idiopathic VTE
Residual DVT
Elevated D-dimer levels
Age
Gender

12. Hereditary Risk Factors

13. Antithrombin Deficiency
(previously known as Antithrombin III)
Inhibits coagulation by irreversibly binding the thrombogenic proteins thrombin (IIa), IXa, Xa, XIa and XIIa
Antithrombin binding reaction is amplified 1000-fold by heparin, which binds to antithrombin to prevent clot formation by avidly binding thrombin and the other serine proteases
An autosomal dominant inheritance
Most thrombogenic disorder! IMP.

15. Protein C Deficiency
Protein C is a vitamin K dependent glycoprotein produced in the liver
In the activation of protein C, thrombin binds to thrombomodulin, a structural protein on the endothelial cell surface
This complex then converts protein C to activated protein C (APC), which degrades factors Va and VIIIa, limiting thrombin production
For protein C to bind, cleave and degrade factors Va and VIIIa, protein S must be available
Protein C deficiency, whether inherited or acquired, may cause thrombosis when levels drop to 50% or below
Protein C deficiency also occurs with surgery, trauma, pregnancy, OCP, liver or renal failure, DIC,or warfarin

16.  When patients with factor 5 Leiden use estrogen pills this causes SEVERE THROMBOSIS IMP!!
 Protein C levels become high due to compensatory effect. [So, both high and low levels of PC lead to
thrombosis].

17. Protein S Deficiency
Protein S is an essential cofactor in the protein C pathway
Protein S exists in a free and bound state
60-70% of protein S circulates bound to C4b binding protein
The remaining protein S, called free PS, is the functionally active form of protein S
Inherited PS deficiency is an autosomal dominant disorder, causing thrombosis when levels drop to 50% or lower

19. Causes of Acquired Protein S Deficiency
May be due to elevated C4bBP, decreased PS synthesis(synthesized in the endothelium), or increased PS consumption
C4bBP is an acute phase reactant and may be elevated in inflammation, pregnancy, SLE, causing a drop in free PS
Functional PS activity may be decreased in vitamin K deficiency, warfarin, liver disease
Increased PS consumption occurs in acute thrombosis, DIC, MPD, sickle cell disease
It is a vitamin K dependant protein

20. Factor V Leiden → Activated Protein C (APC) Resistance
Activated protein C (APC) is the functional form of the naturally occurring, vitamin K dependent anticoagulant, protein C
APC is an anticoagulant which inactivates factors Va and VIIIa in the presence of its cofactor, protein S
Alterations of the factor V molecule at APC binding sites (such as amino acid 506 in Factor V Leiden) impair, or resist APC’s ability to degrade or inactivate factor Va

22. Prothrombin G20210A Mutation
A G-to-A substitution in nucleotide position is responsible for Prothrombin (factor II) polymorphism
The presence of one allele (heterozygosity) is associated with a 3-6 fold increased for all ages and both genders
The mutation (hetrozygous)causes a 30% increase in prothrombin levels(very high).
Prothrombin 20210A mutation is the 2nd most common prothrombotic mutation (antithrombin resistance )

24. Hyperhomocysteinemia
Hyperhomocysteinemia could be inherited or acquired ( deficiency of Vitamin B12, B6 and B8, IBD , Intrensic factor, RBCs damage , drugs, Methionine synthase deficiency ,
MTHFR (methyline tetra hydro folate reductase )Mutation, TB medication
Implicated in both arterial and venous thrombosis.
Treatment is by administering folic acid.
Acquired is more common than inherited.
 Rare autosomal recessive disorder
Can cause CAD
Tetrahydrofolate
The pathophysiology of thrombosis in hyperhomocysteinemia is also unclear. Proposed mechanisms include direct endothelial injury, increased tissue factor activity, inhibition of protein C activation, increased platelet activation and aggregation, suppression of thrombomodulin expression, and impaired fibrinolysis by inhibition of tPA binding to its endothelial cell receptor.

25. Antiphospholipid Syndrome
Anti phospholipid syndrome is the most important acquired cause of thrombotic disorders

26. Antiphospholipid Syndrome— Diagnosis
Clinical Criteria
Arterial or venous thrombosis
Pregnancy morbidity ( recurrent fetal loss )
Thrombocytopenia
Laboratory Criteria
IgG or IgM anticardiolipin antibody-medium or high titer
Lupus Anticoagulant
b2 microglobulin
Must establish at least one from each of these 2 criteria

27. Antiphospholipid Syndrome— Clinical
Thrombosis—arterial or venous
Pregnancy loss
Thrombocytopenia
CNS syndromes—stroke(the most common arterial event), chorea
Cardiac valve disease
Livedo Reticularis

28. Antiphospholipid Syndrome— The Lupus Anticoagulant (LAC)
DRVVT- venom activates F. X directly;
prolonged by LAC’s
APTT- Usually prolonged, does not correct in 1:1 mix
Prothrombin Time- seldom very prolonged
The Sapporo criteria require at least one of the above laboratory tests to be positive and the patient to have at least one clinical manifestation of antiphospholipid syndrome such as vascular thrombosis or fetal mortality/morbidity in order to diagnose the antiphospholipid syndrome (also known as Hughes syndrome).[7] Positive laboratory test results should be seen on two separate occasions at least twelve weeks apart in order for diagnosis.

29. Role of phospholipids on Coagulation Tests

30. ↑PTT

31. Antiphospholipid Syndrome— Anticardiolipin Antibodies
ACAs are antibodies directed at a protein-phosholipid complex
Detected in an ELISA assay using plates coated with cardiolipin and B2-glycoprotein

32. Antiphospholipid Syndrome— Treatment
Patients with thrombosis- anticoagulation, INR 3
Anticoagulation is long-term —risk of thrombosis is 50% at 2 years after discontinuation
Women with recurrent fetal loss and APS require LMW heparin and low-dose heparin during their pregnancies

33. Heparin-Induced Thrombocytopenia (HIT)
HIT is mediated by an antibody that reacts with a heparin-platelet factor 4 complex to form antigen-antibody complexes
These complexes bind to the platelet via its Fc receptors
Cross-linking the receptors leads to platelet aggregation and release of platelet factor 4 (PF4)
The released PF4 reacts with heparin to form heparin-PF4 complexes, which serve as additional sites for HIT antibody binding

34. Diagnosis of HIT Diagnosis made on clinical grounds
HIT usually results in thrombosis rather than bleeding ( DVT and PE )
Diagnosis should be confirmed by either immunoassay( anti-platelet factor VI by ELISA) or functional tests (14C serotonin release assay)
Treatment involves cessation of heparin, treatment with an alternative drug, e.g. argatroban( direct thrombin inhibitor ), and switching to warfarin

35. ↑Tissue factor (Cancer)

36. TFPI

37. Clinical Implications In Treatment of Thrombophilia
Routine screening of patients with VTE for an underlying thrombophilic defect “is not justified”
However, the risk of subsequent thrombosis over 5 years in men with idiopathic VTE is 30%
Any additional defect adds to risk and to possible need for prolongation of anticoagulation
Furthermore, women with a history of VTE who wish to become pregnant will be treated differently if a defect were found

38. Screening Evaluation For “Strongly Thrombophilic” Patients
Test for Factor V Leiden
Genetic test for prothrombin gene mutation 20210A
Functional assay of Antithrombin
Functional assay of protein C
Functional assay of protein S
Clotting test (coagulation assay )for lupus anticoagulant/ELISA for cardiolipin antibodies
Measurement of fasting total plasma homocysteine

39. Screening Laboratory Evaluation For “Weekly Thrombophilic” Patients
Test for Factor V Leiden
Genetic test for prothrombin gene mutation G20210A
Measurement of fasting total plasma homocysteine
Clotting assay for lupus anticoagulant /ELISA for cardiolipin antibodies

40. Management of Patients With Thrombophilia
Risk Classification Management
High Risk
2 or more spontaneous events Indefinite Anticoagulation
1 spontaneous life-threatening
event (near-fatal pulmonary
embolus, cerebral, mesenteric,
portal vein thrombosis)
1 spontaneous event in association
with antiphospholipid antibody
syndrome, antithrombin deficiency,
or more than 1 genetic defect
Moderate Risk
1 event with a known provocative Vigorous prophylaxis in
stimulus high-risk settings
Asymptomatic

41. Heparin

42. Both are direct factor Xa inhibitor. For prevention

44. Diagnosis of Thrombophilia:
 Usually they are diagnosed with venous thrombotic embolization
 DVT and pulmonary embolism are the two most common manifestations of the same disease: VTE
  Imaging: Duplex, spiral CT (Test of choice for PE diagnosis), Magnetic resonance venography, etc
 Echocardiography, ventilation-perfusion (V/Q) scanning, and pulmonary angiography.
 D-dimer Useful in low pre-test probability to exclude diagnosis of VTE
Sensitivity and negative predictive value are high (~99%)
 Laboratory tests: PT, PTT, protein C, S, AT (almost always low with acute thromboembolic episodes), homocysteine, anticardiolipin, factor V Leiden, FII mutation, (JAK2 mutation).

45. Treatment:
1. Anticoagulation:
a. Heparin:
 MOA: potentiates the action of antithrombin to inhibit clotting factors II and X.
 Monitored by PTT because it prolongs it.
 ADRs: bleeding, heparin-induced thrombocytopenia(HIT) this PE and DVT, osteoposrosis, alopecia.
 5-Contraindications:previous HIT, active bleeding, haemophilia, TCP, HTN, recent surgery on eyes or brain.
 6-Antidote for overdose: protamine sulphate
b.Low-molecular weight heparin LMWH:
 MOA: inhibit factor X directly.
 Administered subcutaneous.
 They cannot be monitored by PT or PTT (they affect neither)
 Less monitoring needed
 contraindicated in Stage V CKD.
c. Warfarin (oral anticoagulant)
 MOA: Vitamin K antagonist – leads to decrease in vitamin K-dependant clotting factors ( II, VII, IX, X) and protein C and S.
 Monitored by PT because it is prolongs it.
 Also monitored by INR (2-3 is therapeutic).
 iv. Takes 4 or 5 days to have full effect so start heparin first.
 ADR’s: TERATOGENIC (avoid in pregnancy)
 Antidote for overdose: stop warfarin and give vitamin K.
 Direct thrombin inhibitors (ximelagatran)
 Factor Xa inhibitors (fonduparinux).
2. Thrombolysis: Tissue plasminogen activators (t-PA, u-PA, urokinase, alteplase)
3. Thrombectomy (arterial).