Drugs like warfarin have been used as a poison because they cause bleeding. But the warfarin, as far as I know, don’t cause bleeding they just stop blood from clotting.
So does the human body suffer injuries everyday that cause bleeding, but just end up getting clotted up? if so, what kinds of injuries cause this? Or rats, how can rats die from internal bleeding unless they’ve been injured in some way and the warfarin prevents the blood from clotting?
I was under the impression that a person only bled if they had a bruise or a cut. But does a person have microbleeds everyday just over the course of a normal day? capillaries burst, arteries develop leaks, organs get injured, etc?
Why is an extremely large dose of a drug like warfarin fatal when hemophilia isn’t automatically fatal?
Yes. There is spontaneous bleeding in the sense that it is not due to any typical external trauma and can arise from things like sneezing, activities of daily living (walking, coughing, straining), or possibly even what are usually inconsequential microhemorrhages.
Basically, as you have inferred, if a rat on warfarin bleeds to death in the absence of any external trauma, there must be spontaneous bleeding, or at least there’s bleeding that would have normally been repaired immediately and having no lasting effect.
Unfortunately we see this in people not infrequently. Most common nowadays is in people on warfarin and other medications that impair blood coagulation. It also happens in people with leukemia (and other cancers) where either the cancer or its treatment has devastated the other arm of blood clotting, the platelets.
No. Blood loss in that setting is from destruction of the red blood cells themselves (hemolysis) due to mechanical trauma. But all the broken down blood, or at least its constituents’, remain in the body (until the breakdown products are excreted).
That said, iron entering the bloodstream in this way is lost from the body and is a rare cause of iron deficiency anemia.
ETA: I should have been clear in saying that hemolysis is not considered a form of bleeding, and it is not a consequence of using either anticoagulants (‘blood thinners’) like warfarin or anti-platelet agents such as aspirin and Plavix.
As a younger man I had sudden, unexplained nose bleeds. They’ve now stopped. My 12yo daughter has been getting them for a couple years. The doctors say “it happens.”
A hemorrhagic stroke is spontaneous bleeding in the brain and is the main danger from warfarin and why you have to be tested every 6 weeks. The difference between a therapeutic dose and a dangerous one is slight.
Intracranial hemorrhages are a definite complication of warfarin. They are less frequent than you might expect though, but often devastating when they occur.
For every hemorrhagic stroke in a warfarin user, there’s ten to fifteen episodes of GI bleeding. While far less likely to be fatal or life-changing, they are definitely to be avoided. Often the stress of a GI bleed can, for example, precipitate a heart attack (perhaps not too surprising given that many people on warfarin have underlying heart problems).
Warfarin use is decreasing rapidly and it will probably almost disappear altogether as more and more docs (and patients) become comfortable with newer anticoagulants which do not require any blood test monitoring (e.g. factor X inhibitors such as apixaban and rivaroxaban; thrombin inhibitors such as dabigatran (Pradaxa)). And, since the blood levels of these newer drugs are more stable than those of warfarin, with far fewer interactions with other drugs, there is also less ‘spontaneous’ bleeding in people using them compared to warfarin.