Warfarin + Supra therapeutic INR

Thanks to Ashley Stein-Merlob for presenting a case of a woman on warfarin with some very wild labs and a supra therapeutic INR. Let’s get bread and butter for a moment and talk about ddx/management of a supra therapeutic INR
Etiologies
Divided into things that affect intake, absorption, or metabolism
  • intake
    • taking too much or too little warfarin
    • changes in dietary intake of vitamin k (you could also see this as metabolism but that’s splitting hairs =)
  • absorption
    • diarrhea
  • metabolism`
    • meds that prolong or speed up metabolism
    • illnesses that affect hepatic perfusion (sepsis, decompensated heart failure)
    • new liver dysfunction/failure
  • In the real world, the most common cases are
    • dietary/adherence related
    • heart failure
    • infection
    • diarrhea
Management
  • If bleeding, reverse! Use IV vitamin K, which reverses faster, and FFP vs PCC depending on the tempo, severity and location of the bleeding. Details of this another time.
  • Check out this fancy table from the American College of Chest physicians about managing INR in every imaginable circumstance.
screen-shot-2017-02-03-at-9-08-52-am
A brief digression
This patient’s INR went from 6->1.7 12 hours after receiving oral vitamin K. Is that… wild? Unheard of? Normal?
Turns out the answer is uncommon, but not unheard of. Below is a table from a paper comparing the time to INR reversal for IV and PO vitamin K.
Screen Shot 2017-02-03 at 5.11.00 PM.png
My big takeaways are
  • IV vitamin K works faster and should be used in patients who are bleeding
    • you may have learned in med school that IV vitamin K is associated with a higher rate of anaphylaxis. Larger studies have debunked this myth, so don’t be afraid!
  • 14% of patients have their INR completely reversed within 12 hours with 1 PO dose of vitamin k
Have a fabulous weekend!
References
Meehan R1Tavares MSweeney J. Clinical experience with oral versus intravenous vitamin K for warfarin reversal.Transfusion. 2013 Mar;53(3):491-8

Ansell J1Hirsh JHylek EJacobson ACrowther MPalareti GAmerican College of Chest Physicians.Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. 2008 Jun;133(6 Suppl):160S-198S.

 

Mike Hurley, this bonus paper is for you (I’ll write pearls about this sometime soon):
Mehanna HM, Moledina J, Travis J. Refeeding syndrome: what it is, and how to prevent and treat it. BMJ 2008 vol 336 June. p1495-1498

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