Chapter 39 Coagulation And Fibrinolysis

Front 1

coagulation factors for each of the pathways
Intrinsic:
Extrinsic:
Common:

Back 1

Intrinsic: 12,11, 9,8,10,5,2 and fibrinogen
Extrinsic: 10,7, 5,2and fibrinogen(1)
Common: 10, 5, 2 and fibrinogen(1)

Front 2

Factors 5a and 8a act as cofactors to mediate the activation of other players in the coagulation cascade

Back 2

factor 8a helps 9a activate 10; factor 5a helps 10a activate 2 (trombin)

Front 3

distinguish FDP and D-dimer

Back 3

FDPs may be generated by the degradation of either fibrin or fibrinogen; D-dimers are products of fibrin alone and more specifically indicate that clotting has taken place

Front 4

define the prothrombin time test; what coagulation factors are supplied as reagents

Back 4

PT test: reagent tissue thromboplastin (factor3) is mixed with the patient plasma; (factor 3 activates factor 7 in the extrinsic pathway in normal clotting); then calcium is added as reagent calcium chloride and the time to clot formation is measured

Front 5

True or False. The activated partial thromboplastin time (PTT) asseses physiologic hemostasis by evaluating the contact factors in the intrinsic coagulation system.

Back 5

False; the contact factors in the intrinsic pathway are evaluated BUT the PTT really doesn't assess physiologic homostasis

Front 6

difference between platelet and coagulation defect bleeding

Back 6

Platelet disorders: immediate bleeding, difficulty making the initial platelet plug
Coagulation: delayed bleeding after the breakdown of the initial platelet plug; they cannot generate the complete stable clot

Front 7

explain why a patient with low factor 8 level and no inhibitor, the PTT corrects to reference range; if only half of the plasma in a mixing study contain adequate factor 8, shouldn't the PTT be twice normal?

Back 7

no, only 50% levels of any coagulation factor will result in clotting times that fall within reference range and will ensure adequate hemostasis for routine activities

Front 8

if a normal man has 80% clotting factor activity; how many units/ml of factor does he have?

Back 8

100% activity is equivalent to 1.0 unit/ml so 80% activity is 0.8 units/ml

Front 9

dosing formula for recombinant factor 8 for hemophilia A is :
dose (IU)= body weight(kg) x 0.5IU/kg x percent increas required
Problem: patient with <1% activity , requires 50% activity , weighs 42kg, what is his dose?

Back 9

he'll need 1050IU; 42kg x 0.5IU/kg x (50-0%)= 1050IU

Front 10

45 yow marked prolong PTT on routine screening prior to elective surgery; she has 3 children and tooth extractions without excess bleeding; factor analysis shows one factor decreased; DX?

Back 10

factor 12 deficiency

Front 11

22yom mildlt prolonged PT and PTT on routine screen; increased bleeding with wisdom tooth extraction; fibrinogen antigen assay is within reference range; thrombin time prolonged;DX?

Back 11

dysfibrinogenemia; qualitative defect of fibrinogen; these patients have mild bleeding

Front 12

acquired factor deficiency in 8.7%percent patients with amyloidosis?

Back 12

factor 10

Front 13

couple with four children;
Andrew moderate hemophilia A with usual factor levels 4-5%
In the ratio of factor 8 to vWF (normally 1:1)
Three daughters would like to know if they are carriers?
Anne: 0.45
Betty: 0.52
Cecilia: 1.09

Back 13

test that will help is the ratio of factor 8 to vWF; normally it is 1:1; (vWF is a carrier for factor 8, they circulate in pairs); in carriers of hemophilia A who have factor levels of about 50%; this ratio is roughly 0.5:1.0; thus Anne and Betty appear to be carriers, Cecilia is not

Front 14

which routine screening and confirmatory tests are normal and which are abnormal in factor 13 deficiency?

Back 14

the PT and PTT are normal because the test ends with the formation of the fibrin monomer; crosslinking need not occur; in normal persons fibrin clots(crosslinked polymers)are stable in a solution of 5M urea; in factor 13 deficiency the clot will dissolve in 5M urea

Front 15

severe hemophilia A patient is known to have developed an inhibitor to factor 8; inhibitor was measured at 2 Bethesda units;he is given a dose of recombinant factor 8 that would raise his level to 100% if he had no inhibitor; expected factor 8 level?

Back 15

if severe hemophilia consider the starting factor level to be 0-1%;after the dose is given factor 8 will be near 25%; each Bethesda unit reduces the amount of factor 8 activity by one half;
here he went from 100 to 50, then 50 t 25 with 2 Bethesda units