What clotting factor would be deficient if a person had a prolonged prothrombin time?

Question

(this person had a normal partial thromboplastin time) Is there any way to find the missing clotting factor or could there be many???)

Answer 1

there could be a few, prolonged pt follows the extrinsic pathway for clotting. so could be a deficiency in any of the following factors: 8, 9, 11, 12. these factors are PTT specific. deficiency in 8 is normally classic hemophilia and deficiency in 9 is non classic hemophilia. however women aren't hemophiliacs, but can be carriers of the gene for it.

these factors are made in the liver by vitamin K. we get vitamin K from bacteria in our digestive tract.

the previous poster was correct in stating coumadin can prolong it, but i'm guessing you aren't taking that med, correct?

update: because factor 7 and 10 are related to both pathways (PT and PTT) this would lead me to believe you wouldn't have a deficiency in either of these (as your PTT is normal). As far as how you determine which is missing, the post after me describes the test accurately

Answer 2

There are two pathways for the clotting sequence. The intrinsic and extrinsic. The prothrombin time (PT) measures the activity of the extrinsic pathway. Factor VII activates factor X which converts prothrombin to thrombin. Thrombin then activates fibrinogen to form fibrin polymers that make up the blood clot. In prolonged PT times, the problem can be due to a deficiency in factor VII. Since factor X is common to both pathways, a deficiency in that factor would result in a prolonged partial thromboplastin time (PTT) as well as prolonged PT. The two other above mentioned factors are also common to both pathways. There are specific factor assays that test for a deficiency. Basically how it works is a certain factor is added to the test sample and if it corrects the PT time then that factor was deficient. There can be inhibitors, such as drugs or antibodies that can block the activity of some of the factors which can prolong the PT time. There is a simple test to differentiate between a factor deficiency or an inhibitor called a mixing study. That is where normal patient plasma is mixed with the test patients plasma and tested. If the clotting time is corrected to normal or near normal, then the problem is a factor deficiency. If the clotting time is not corrected then the problem is due to an inhibitor. Hope this helps.

Answer 3

Prolonged Pt

Answer 4

Usually that would mean the person was taking coumadin. It's a factor VII deficiency, I believe, though, if they are not on coumadin. Here's some more info:

http://www.hemophilia.org/NHFWeb/MainPgs/MainNHF.aspx?menuid=187&contentid=50&rptname=bleeding