INR increasing...without anticoagulation?

KBICU · Jun 30, 2012

Is it possible the pt is taking another drug to cause this? Did the docs order a redraw to make sure it was a true value?

interleukin · Jun 30, 2012

INRs take time to crest and fall even when a patient has stopped taking coumadin.

It can also be affected by liver or clearance issues.

Double-Helix, BSN, RN · Jun 30, 2012

A little research into the action of Warfarin showed that the peak effect could be delayed 72-96 hours from the time it's given.

There also could be some dietary effects. If the patient usually eats some foods with Vitamin K at home or takes a multivitamin, but they don't continue to take this in the hospital, the Warfarin that is already in their system could have a more potent effect. That's just a thought, though. I didn't look for research that supports that.

LetsChill · Jun 30, 2012

I don't remember a lot of details but one pt whom this happened to was being anticoagulated for B PE and DVT, had ca with post op sepsis, endocarditis. Cancer screws up everything, but the INR was probably (hopefully) just peaking.

I think with another pt with this scenario it took several more days, after having peaked, to lower the INR to a therapeutic level. I guess patience wins the race.

Thanks guys! Don't stop learning.

nurse678 · Jun 30, 2012

Also what are his LFT's? Could be liver issues possiblly.

LetsChill · Jun 30, 2012

INRs take time to crest and fall even when a patient has stopped taking coumadin.
It can also be affected by liver or clearance issues.

Not sure about pts LFTs but creatinine was up for sure, but slowly improved. Clearance probably played a role too. Good call.

burghrn · Jul 1, 2012

Liver. DIC.

Parsifal · Jul 1, 2012

A simple answer to this could be that this 'septic' patient was on antibiotics. This is often an overlooked cause of elevated INR. Some ABTs are actually more likey than others to cause this (cipro is one that sticks out in my mind)..

And the reason ABTs do this is actually quite simple and easy to understand.

One major way our bodies acquire vitamin K is that some of the normal flora/bacteria in our colons/GI-tract produce it. (yuck). Wipe out this beneficial bacteria with ABTs and patient loses this source of VitK... INR can elevate.

Sometimes its as simple as that.

LetsChill · Jul 1, 2012

A simple answer to this could be that this 'septic' patient was on antibiotics. This is often an overlooked cause of elevated INR. Some ABTs are actually more likey than others to cause this (cipro is one that sticks out in my mind)..
And the reason ABTs do this is actually quite simple and easy to understand.
One major way our bodies acquire vitamin K is that some of the normal flora/bacteria in our colons/GI-tract produce it. (yuck). Wipe out this beneficial bacteria with ABTs and patient loses this source of VitK... INR can elevate.
Sometimes its as simple as that.

Awesome explanation. Thanks. I had no idea. I don't remember if the pt was on one of these antibiotics.

InteractionPotential effectTime to effectRecommendations and comments

Warfarin (Coumadin) plus ciprofloxacin (Cipro), clarithromycin (Biaxin), erythromycin, metronidazole (Flagyl) or trimethoprim-sulfamethoxazole (Bactrim, Septra)

Increased effect of warfarin

Generally within 1 week

Select alternative antibiotic.

Don't stop learning y'all!

nerdtonurse?, BSN, RN · Jul 2, 2012

Also, if the patient has cancer, they usually have low albumin (either d/t the disease process or malnutrition); low albumin can affect protein binding, making more warfarin stay in the system longer. I know seems particularly tricky to anticoag someone with GI CA and liver CA who need something due to afib, artificial valves, etc. Lovenox works better than warfarin in those cases, in my experience.

nyrn5125 · Jul 2, 2012

Exacly what I was thinking. Once had a patient that was getting multiple doses of vit k and the inr was still 13. He was on Cipro