Here is one of our April 22, 2018 Medical Laboratory Professionals Week case studies for your response. Watch for more “Lab Week” case studies in the weeks ahead!
I (George) have corresponded with a gentleman since 2009; we’ve developed an electronic friendship, though we’ve never met F2F.
“John” first contacted me in 2009, a year after Precision BioLogic and I launched Fritsma Factor. John is a professional man who claims to be overweight but who plays ice hockey for recreation. A puck hit him in the calf in 2009, and when the pain and swelling persisted, he saw his primary care physician who ordered an ultrasound, which indicated deep vein thrombosis. John’s doctor started him on a round of Coumadin therapy and monthly PT/INRs. His treatment course was uneventful, and after the Coumadin was discontinued he had a thrombophilia workup that returned normal results except for homocysteinemia. John took over the counter folate, vitamin B6, and vitamin B12 plus a baby aspirin but had discontinued all four sometime along the way. He continues to play hockey.
On February 10, 2018, John experienced new pain in the location of the old clot, this time not related to his physical activities—that is, no identifiable trigger. His primary had retired, so he saw an ER doctor, who ordered a new ultrasound. The radiologist read the old DVT location as having two consolidated clots and one new one. Neither doctor had access to the 2009 image, only a written summary. On the basis of the new finding, John was prescribed Xarelto (rivaroxaban), which he is continuing, and which he reports causes more profuse and prolonged bleeds subsequent to shaving nicks than did the Coumadin. He has been offered no laboratory assay. John is retired, but when he was working he traveled often and never had a travel-associated DVT.
Here are John’s questions, which I paraphrase…
- · How accurate is his new diagnosis?
- How long will he be required to stay on Xarelto?
- · What are the Xarelto bleeding characteristics?
- · How is Xarelto best measured, and what is the value of assaying Xarelto?
- · Should he have a new set of thrombosis risk tests? Which should be repeated?
- · Could the new episode indicate onset of a new risk factor such as lupus anticoagulant or cancer?
A 6/14/18 update from “John.”
A 6/14/18 update from “John.”
I went back to the Doctor after being on Xarelto for 90 days and he had a more thorough ultrasound completed on me. This method checks for blood flow rates in both legs in addition to the typical ultrasound.
The appointment sans the test was actually very brief. He stopped in and mentioned that the tests showed no clotting beyond the scarring/damage that likely was the result of my first event….a portion of my popliteal vein and also my upper saphenous vein (essentially where the puck hit me). I do have some lifelong venous insufficiency due to the scarring–my left leg appears to be clean as a whistle.
His direction to me was to continue increasing exercise and also that I take measures to lose weight.
In summary I am not absolutely certain if he ever felt that I had true second clot–his observation was that given the large amount of travel and lack of clotting during that time it is most likely that any current issue was driven by a sedentary lifestyle and excessive weight–if I can manage those areas of my life better my risk of recurrence should be minimized.
I was curious about the one commentators’ statement that blockages of the popliteal don’t count? What does that mean?
Thinking back to my initial observation of bleeding more profusely on Xarelto–my observation occurred very early in my treatment when I was taking the ramp up dosage of Xarelto. I think it was 15 mg twice daily. Then it tapered off to 20 mg once daily. I also think that when I nicked myself I was not that far removed from taking a dose–so from a half life perspective I was was likely at close to a peak concentration–perhaps that relates to the bleed rate I observed.
From Bob Gosselin: How
From Bob Gosselin: How accurate is his new diagnosis? How long will he be required to stay on Xarelto? Males have high rate of occurrence, but curious about calf DVT–if distal to popliteal, does this really count?
What are the Xarelto bleeding characteristics? Not sure what this means–always a bleeding risk with anticoagulants. How is Xarelto best measured, and what is the value of assaying Xarelto? Best assessed by trough collections using either tandem mass spec or drug calibrated anti-Xa.
Should he have a new set of thrombosis risk tests? Which should be repeated? No–low yield–given that he is retired, this would imply elderly, so why assess for thrombophilia w/u. Boys have higher rate of recurrence than girls.
I think John should go back
I think John should go back and see his doctor–perhaps acquire a new primary care physician. He would best be able to answer the questions around accuracy of diagnosis, although I would be also guided by the radiologist, who is the expert in reading (ultrasound) images. I am concerned about the reported bleeding. As these drugs are cleared by the kidney, there is a danger of drug accumulation if there is renal impairment. John could have a test for drug level done, to assess for drug accumulation, but it would be important to do this with full knowledge of drug dose and time of last ingestion. If John shaves within 3 hours of taking the drug, this would be at peak plasma levels. If he tries to shave (instead) an hour before taking the drug, this would be at trough levels, then if bleeding does not occur, this may provide some evidence of an association. But in the end, I would recommend he goes back under the care of a new primary care physician and have the whole situation sorted out properly!