Cp2, Disorders Of Hemostasis And Thrombosis

Front 1

What are the components of hemostasis

Back 1

complex, relies on multiple serum proteins (clotting factors), vascular endothelium and cellular components of blood (platelets) for proper funcion.

Front 2

definition of hemostasis

Back 2

complex interaction of both loval and systemic factors which culiminates in arrest of bleeding at sites of vascular injury. (primary and secondary mechanisms)

Front 3

primary hemostasis

Back 3

interaction between platelets and the vascular endothelium. serum coagulation factors are not involved.

Front 4

secondary hemostasis

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involves serum coagulation factors, which also recruit platelets and amplify oth primary and secondary hemostasis

Front 5

Med Hx for bleeding disorders

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history of bleeding (gums, joints, urine, , stool) hx easy bleeding, bleeding after surgery

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thrombocytopenia

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most common bleeding disorder. generally refers to platelet count <100,000 **test question**

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2 categories of thrombocytopenia

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1) decreased production/increased destruction
2) sequestration-->from hypersplenism

Front 8

pseudothrombocytopenia

Back 8

in vitro platelet clumping from EDTA tube. should review smear, collect in heparin or citrate tube.EDTA binds and ties up the platelets and the machine that counts it filters it out without counting correctly.

Front 9

decreased megakaryocytes in marrow causes;

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can cause decreased production of platelets (megakaryocytes make platelets)

Front 10

what can cause decreased megakaryoctyes

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marrow infiltration (malignancy, myelofibrosis) marrow hypoplasia (chemicals or drugs, radiation, infection)
congenital (fanconi's anemia, TAR syndrome)

Front 11

causes of increased destruction of platelets

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drug-induced, idiopathic cytopenia purpura, DIC

Front 12

what drugs are implicated in drug-induced thrombocytopenia

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Heparin, digitalis and digoxin, sulfonamides, ASA, Quinine and quinidine, cephalosporin antibiotics, lasix

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4 most common causes of thrombocytopenia ***

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1) heparin
2) digitalis and digoxin
3) loop diruetics (lasix)
4) H2 blockers (ex/tagament)

Front 14

idiopathic thrombocytopenia purpura

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occurs in absence of a known agent. history of viral URI can be elicited in over 80% of cases.
most common in children, but occurs in adults as well

Front 15

treatment of idiopathic thrombocytopenia purpura

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1) Steroids-->prednisone usually causes rise of platelets to normal within 1-2 weeks.
2)IVIG-->saturates Fc receptors in the RES (reticular endothelial system) and brings promp response in over 80% of cases. (1 round cost about $5000)
3) last ditch effort is to remove the spleen

Front 16

DIC

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fatal in 80% of cases
initial thrombosis stage, followed by active bleeding stage

Front 17

treatment of DIC

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correct underlying disorder, most common is sepsis.
heparin--not usually used unless overt thrombosis occurs
supportive care, platelet and factor replacement

Front 18

thrombotic thrombocytopenia purpura

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generalized disorder of the microcirculation characterized by thrombocytopenia purpura, microangiopathich hemolytic anemia, fluctuating neurological signs, renal dysfunction, and febrility.

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difference between TTP and hemolytic uremic syndrome

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TTP=MAHA and thrombocytopenia <50,000 and fever and neuro symptoms
Hemolytic uremic syndrome=add renal failure

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signs and symptoms of thrombotic thrombocytopenia purpura

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Microangiopathic anemaia= schistocytes, helmet cells. known as waring blender effect.
pathological lesion=hyaline thrombi which occlude the capillaries of virtually every organ in the body.
linked to infection, surgery , pregnancy

Front 21

difference between TTP and DIC

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clotting times in DIC are abnormal but are normal in TTP

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treatment for thrombotic thrombocytopenia purpura

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1) treat the cause
2) plasmapheresis-->life saving in virtually 100% of cases
mortality virtually 100% if not treated

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von Willebrand's disease

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very close relationship with factor 8.
affected pts present with prolonged bleeding time.
platelet aggregation tests are abnormal)

Front 24

treatment for vonWillebrand's disease

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1) cryoprecipitate=replaces vWF
2)DDAVP=causes release of vWF from blood vessel endothelium

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Hemophilia A

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x-linked deficiency of factor 8. deficiency is variable, from modest amt to complete absence of the factor.Risk of bleeding corresponds to degree of factor deficiency.

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clinical features of hemophilia A

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easy bleeding and bruising. hematomas, hemarthroses, increased bleeding after surgery.

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treatment for hemophilia A

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factor replacement for bleeds and surgical prophylaxis (factor 8), recombinant factor replacements

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Hemophilia B

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like A, except these patients have factor 9 deficiency. same presentation otherwise

Front 29

deficiency of vitamin K dependant clotting factors

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occurs in patients taking warfarin. also in patients on chronic antibiotics (sterilize the gut and causes loss of vit K secreting bacteria), severe liver disease

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what factors are deficient in vitamin K-dependent factors?

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*** Factors II, VII, IX, X , protein C and S

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antithrombin III deficiency

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patients deficient in AT-III convert more prothrombin to thrombin and have increased tendency for clotting.

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Treatment for antithrombin III deficiency

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prophylactic tx with antcoagulants-->warfarin/coumandin for life. pts with DVT get heparin at higher doses.

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clinical symptoms of antithrombin III deficiency

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typically minimal until early death from recurrent pulmonary emboli. 1/2 pts have 1st DVT by 30 y/0

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protein C and Protein S

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are normal anti-coagulants
protein C=inactivates factors V and VIII
protein S=cofactor for protein C

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deficiency of protein C and S

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pts with deficiencies of protein C or S have similar clinical course and presentation as Antithrombin III deficiency

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what is the most common cause of hypercoagulable state from deficiency of protein C and S

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initiation of warfarin therapy. protein C and S are depleted prior to the other factors, resulting in a temporary increase in coagulability

Front 37

Factor V Leiden

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abnormality of factor 5 at binding site for activated C protein. risk for thromboembolic disease. treatment is lifelong coagulation

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Antiphospholibit syndrome

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poorly understood constellation of disorders that have their cornerstone as the presence of circulating antibodies to phospholipid

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diagnosis for antiphospholipid syndrome

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3 tests
1) PTT test (prolonged phospholipid-dependent coagulation test)
2) lack of correction in mixing studies using normal plasma (lack of correction means antibodies are present, if corrected means clotting factors were missing)
3) neutralization of inhibitor with excess phospholipid (excess phospholipid overcomes the antibody)

Front 40

Virchow's triad

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results in thrombosis
1)vascular injury
2)hypercoagulability
3)change in flow (venous stasis)

Front 41

What is the most common bleeding disorder?**

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Thrombocytopenia **

Front 42

What 4 major drugs are implicated in drug-induced trhombocytopenic purpura? ***

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!) heparin
2) Digitalis and digoxin
3) Loop diuretics (lasix)
4) H2 blockers

Front 43

What factors are vitamin K dependent and are deficient in vitamin k dependent factor deficiency? **list all 6**

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Factors II, VII, IX, X protein C and S

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what is antiphospholipid syndrome

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a constellation of disorders that have the presence of circulating antibodies to phospholipids

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what are some associated features of antiphospholipid syndrome

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miscarriage, thrombocytopenia, cerebral ischemia and recurrent stroke (especially in young patients) UBO on MRI scans (unidentified bright objects)

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RES system

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reticular endothelium system-->makes antibodies

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antiphospholipid antibodies do what?

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interfere with the clotting cascade. antibodies against our phospholipids, so we form more clots. In anti-phospholipid syndrome our patients will form MORE clots.

Front 48

what tests will be effected in antiphospholipid syndrome?

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prolonged PTT time, lack of correction in mixing studies, neutralization of inhibitor with excess phospholipid

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Why is PTT time prolonged in antiphospholipid syndrome?

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these autoantibodies also just happen to bind to the phospholipid part of the PTT reagent (and sometimes, the PT reagent). Then there’s not enough usable reagent in the test tube, and the patient’s specimen doesn’t clot! The coagulation tests are therefore falsely prolonged.

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If a pt has a prolonged PTT what might you consider to be the problem>

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1) too much heparin
2) antiphospolipid syndrome
3)coagulation factor deficiency (hemophilia)

Front 51

what is the most common inherited thrombophelic disease. effects 6-10% of general population.

Back 51

factor V Leiden

Front 52

incidence of hereditary relative risk factors for prob of a first DVT or pulmonary embolism

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cancer, birth control, phosphoantilipid Abs,
1) General population risk=1
2) 5x increased risk for heterozygous factor V leiden
3) heterozygous prothrombin mutation=5x risk
4) protein C and protein S=about 10 times greater
5) 20x in antithrombin deficiency
5) homozygous factor V=80 fold increase!!!

Front 53

acquired risk factors for first DVT

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1) estrogen therapy=4 fold increase in risk
2) hypohomocystinemia=double risk
3) cancer=7 fold increase in risk

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what is relative risk for first DVT if taking oral contraceptives?

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4x general population risk

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risk of arterial thromboembolic disease

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is not effected like venous thrombi

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2nd or more clot that is unprovoked is treated with:

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life time anti-coagulation treatment