^^ good..
there are a number of reasons to use above tests..
as you may already know that there is an intrinsic and extrinsic blood coagulation pathway.. in a simple diagram:
This is a delicate system meant to insure a constant balance of blood clotting and dissolution.. for your purposes all you need to know to differentiate between the two is that one is activated through injury (extrinsically) from the outside, while the other is formed due to a response to an abnormality in the vasculature..
now there are alot of steps and many many factors that play part in this, and many medications that work on different pathways, whether it is
Glycoprotein IIb/
IIIa working on the receptor found on the surface of the platelet or warfarin which works on factors 2, 7, 9 and 10 from the above pathway and by the way is used in rat poisoning though I digress.. now for various medical conditions a person needs to go on one form of medication as the above in one form or the other, they must check their labs often for when you exceed the limits and the limits in an of themselves vary per condition for instance someone who has had a valve replacement doesn't need to be kept on the same values as someone who has had a hip replacement (so don't be alarmed if the limits seem to far exceed the recommended value) but so that one will either run the risk of forming a clot or bleeding to death and that is really the distillate of a very complex delicate system.. but that is really it in a nutshell keeping within certain values to avoid either of those risks..
I hope insha'Allah that was of help to you?
and may Allah swt grant all Muslims shifaa, both in the mind and body..
:wa: