However, the PT/INR is a better test for monitoring patients on Coumadin, and the PTT is a better test for monitoring patients on heparin, for the following reasons. Coumadin affects all the vitamin K dependent coagulation factors. However, these factors have different half-lives.
http://www.pathologystudent.com/?p=6519
Coumadin works by inhibiting the vitamin K dependent coagulation factors. Several factors in the cascade (II, VII, IX and X) need to be carboxylated in order to bind calcium (which is intimately involved in the cascade).
http://www.pathologystudent.com/?p=6519
What are PT, PTT and INR blood tests? Before you have surgery your doctor may order blood tests to determine how quickly your blood clots. This group of tests is known as a coagulation study, individually these tests are commonly referred to as a PT (Prothrombin Time), PTT(Partial Thromboplastin Time), and INR (International Normalized Ratio).
https://www.verywell.com/what-do-your-pt-ptt-and-inr-results-mean-3157005
Factor VIII is manufactured in the endothelial cells of the blood vessels. We see a prolonged PT/INR and PTT/APTT in patients with cirrhosis of the liver (liver failure) when the clotting factor pool has dropped below 50% of normal. Factors II, VII, IX, and X are vitamin K dependent clotting factors.
http://ocw.tufts.edu/Content/24/labs/312447
Also Known As. 1  Activated Partial Thromboplastin Time (aPTT) and Prothrombin Time (PT), PT and aPTT, PT and PTT.A. 2  The prothrombin time (PT) w/INR test measures the length of time it takes for a blood clot to form in a sample of blood. Partial Thromboplastin Time (PTT) test is ordered when someone has unexplained bleeding or clotting.
https://www.walkinlab.com/prothrombintime-pt-winrandpartialthrombopla.html
Note: All of the clotting factors except VIII are produced in the liver. 1  Factor VIII is manufactured in the endothelial cells of the blood vessels. 2  We see a prolonged PT/INR and PTT/APTT in patients with cirrhosis of the liver (liver failure) when the clotting factor pool has dropped below 50% of normal.
http://ocw.tufts.edu/Content/24/labs/312447
I saw that an increased PT would result from Coumadin and Heparin. Do these both work to activate ATIII and therefore effect the extrinsic pathway? I then saw that PTT can be increased as a result of heparin as well, so I am confused as to where heparin works and what effect is has on the coagulation cascade.
http://www.pathologystudent.com/?p=6519
PT/INR and PTT/APTT. 1  These blood tests check clotting factor function. 2  Partial thromboplastin time or activated partial thromboplastin time (PTT/APTT) measures the activity of the intrinsic and common pathways. 3  The normal range of PTT is 25–38 seconds.  This test checks factors XII to I (fibrin).
http://ocw.tufts.edu/Content/24/labs/312447
Prothrombin time. The prothrombin time (PT)—along with its derived measures of prothrombin ratio (PR) and international normalized ratio (INR)—are assays evaluating the extrinsic pathway of coagulation. This test is also called ProTime INR and PT/INR.
https://en.wikipedia.org/wiki/Prothrombin_time
Activated Partial Thromboplastin Time (aPTT) and Prothrombin Time (PT), PT and aPTT, PT and PTT.A. Quick Overview. The prothrombin time (PT) w/INR test measures the length of time it takes for a blood clot to form in a sample of blood. Partial Thromboplastin Time (PTT) test is ordered when someone has unexplained bleeding or clotting.
https://www.walkinlab.com/prothrombintime-pt-winrandpartialthrombopla.html
what is a  pt ptt coagulation cascade needed
The partial thromboplastin time coagulation cascade is needed to determine how quickly your blood clots. A PT PTT coagulation cascade needed to determine how quickly your blood clots.