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Old 01-29-2013
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Default A question about coagulation pathway

Heparin effects Factor 2 and 10 which used by both intrinsic and extrinsic ways of seconder hemostasis.
So, why are we checking aPTT BUT NOT PT?
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Quote:
Originally Posted by Seckinbilgic View Post
Heparin effects Factor 2 and 10 which used by both intrinsic and extrinsic ways of seconder hemostasis.
So, why are we checking aPTT BUT NOT PT?
heparin does not affect factor 7.
factor 7 affects PT not PTT
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both are increased but aptt is more specificaly increases
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Ok then. As I know, coumadin affects on F2,7,9,10. INR(pt) is important. It also affects the way that heparin uses. Why it is not
Important?

Thanks
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Old 01-30-2013
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, heparin mechanism of action is binding and activation of anti thrombin III to cause inactivation of thrombin ( factor II) and factor X so this is the inteinsic clotting pathway represented by aPTT
while warfarin is anti vitamin K causing decrease in factors 2,7,9,10 cause it contains the factor 7 which is the factor of extrinsic pathway it is more markable to look for PT
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Old 01-31-2013
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Please note that warfarin affect factors 1972 so the effects on factors 7 is specific for warfarin and we know that factor 7 is part of extrinsic pathway so it easy to follow the warfarin by PT. But in high dose of warfarin the PTT will also prolong due to effect of warfarin on common pathway factors (1,2)
And the same principle can be
Apply on Heparin
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Quote:
Originally Posted by heartbeat View Post
Please note that warfarin affect factors 1972 so the effects on factors 7 is specific for warfarin and we know that factor 7 is part of extrinsic pathway so it easy to follow the warfarin by PT. But in high dose of warfarin the PTT will also prolong due to effect of warfarin on common pathway factors (1,2)
And the same principle can be
Apply on Heparin
Heparin have No association with extrinsic pathway it affect factor 2 and 10 which don't belong to extrinsic pathway which is 7 which warfarin affect so not the same principle between heparin and warfarin factor 7 make the difference
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Quote:
Originally Posted by menatallah Elgohary View Post
Heparin have No association with extrinsic pathway it affect factor 2 and 10 which don't belong to extrinsic pathway which is 7 which warfarin affect so not the same principle between heparin and warfarin factor 7 make the difference
Thanks menatallah.
As you know that both heparin and warfarin affect factor 2, and also you know that factor 2 located in common pathway of coagulation cascade, so inhibition of factor 2 or any factor in common pathway will prolong both PT and PTT, so this mean that heparin has indirect effect on extrinsic pathway and warfarin has indirect effect on intrinsic pathway, so both heparin and wafarin can cause prolongation of PT and PTT. As you know that warfarin affect factors 1972 but factor 7 has the shortest half life, so if you give a patient warfarin, the first factor that will decrease in activity will be factor 7 , so the best monitor for therapy is PT (extrinsic pathway) which will be prolong first but if you give over dose of warfarin PTT will prolong also and that is not the aim of the therapy. While heparin has more effect on intrinsic pathway with therapeutic dose, so the best monitor for therapy is PTT (intrinsic pathway) but if you overdose the patient, PT will prolong also.

I hope this helpful

Last edited by heartbeat; 01-31-2013 at 10:01 AM.
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Quote:
Originally Posted by heartbeat View Post
Thanks menatallah.
As you know that both heparin and warfarin affect factor 2, and also you know that factor 2 located in common pathway of coagulation cascade, so inhibition of factor 2 or any factor in common pathway will prolong both PT and PTT, so this mean that heparin has indirect effect on extrinsic pathway and warfarin has indirect effect on intrinsic pathway, so both heparin and wafarin can cause prolongation of PT and PTT. As you know that warfarin affect factors 1972 but factor 7 has the shortest half life, so if you give a patient warfarin, the first factor that will decrease in activity will be factor 7 , so the best monitor for therapy is PT (extrinsic pathway) which will be prolong first but if you give over dose of warfarin PTT will prolong also and that is not the aim of the therapy. While heparin has more effect on intrinsic pathway with therapeutic dose, so the best monitor for therapy is PTT (intrinsic pathway) but if you overdose the patient, PT will prolong also.

I hope this helpful
u are correct , well said
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Thanks well explained
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Old 07-07-2014
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Help Intrinsic

Quote:
Originally Posted by heartbeat View Post
Please note that warfarin affect factors 1972 so the effects on factors 7 is specific for warfarin and we know that factor 7 is part of extrinsic pathway so it easy to follow the warfarin by PT. But in high dose of warfarin the PTT will also prolong due to effect of warfarin on common pathway factors (1,2)
And the same principle can be
Apply on Heparin


"But in high dose of warfarin the PTT will also prolong due to effect of warfarin on common pathway factors (1,2)"

and on ___FACTOR 9 ___ which is unique to the INTRINSIC path.

Last edited by juanlink; 07-07-2014 at 12:24 AM.
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