Enoxaparin and Anti-XA levels

[Praziquantel86]

So, we have a bit of an oddball case in our CCU right now. A mid-50s woman was transferred into our hospital after developing pulmonary hypertension and a subsequent PE. She's on Flolan running at about 17ng/min and bosentan. The PE is being treated with enoxaparin 40mg q12 (she's a pretty small woman).

We've been drawing anti-XA levels for the last few days, and each one comes back at about 0.1. The nurse says that the patients been tolerating the injections very well, and the MAR doesn't have any doses missed. We've also made sure that the lab hasn't screwed up.

I've been trying to figure out why the levels are still at pretty much baseline values even with therapeutic dosage. I can't find any literature out there, and any drug interactions would increase the bleeding risk. The attending says that she's seen similar things in pregnant women (she thinks it's hormonal changes in the coagulation cascade), but this patient is definitely not pregnant.

Any ideas?

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[WVUPharm2007]

Is drawing afxa common out there in the rest of the world? That **** is expensive as ****. You must be at one of those academic joints with an unlimited budget.

 

[StaviZFingerZ]

So, we have a bit of an oddball case in our CCU right now. A mid-50s woman was transferred into our hospital after developing pulmonary hypertension and a subsequent PE. She's on Flolan running at about 17ng/min and bosentan. The PE is being treated with enoxaparin 40mg q12 (she's a pretty small woman).

We've been drawing anti-XA levels for the last few days, and each one comes back at about 0.1. The nurse says that the patients been tolerating the injections very well, and the MAR doesn't have any doses missed. We've also made sure that the lab hasn't screwed up.

I've been trying to figure out why the levels are still at pretty much baseline values even with therapeutic dosage. I can't find any literature out there, and any drug interactions would increase the bleeding risk. The attending says that she's seen similar things in pregnant women (she thinks it's hormonal changes in the coagulation cascade), but this patient is definitely not pregnant.

Any ideas?

Well, she did form a clot so her coagulation cascade is out of whack.. at this point instead of worrying about "why," why not treat.. say with unfractionated Heparin protocol to make sure she's properly anticoagulated.

 

[Praziquantel86]

We'll draw them every once in a while when we have a good reason for it. This lady had the PE while she was already on prophylaxis, so I guess the docs wanted to check on that.

Yeah, it's an academic joint. We just got a new ICU, the place is beautiful.

 

[Praziquantel86]

Well, she did form a clot so her coagulation cascade is out of whack.. at this point instead of worrying about "why," why not treat.. say with unfractionated Heparin protocol to make sure she's properly anticoagulated.

There's a reason why we're not, I just can't remember off the top of my head...I'll get back to you tomorrow on that.

At this point, I think it's more for the attendings curiosity than anything else.

 

[WVUPharm2007]

We'll draw them every once in a while when we have a good reason for it. This lady had the PE while she was already on prophylaxis, so I guess the docs wanted to check on that.

Yeah, it's an academic joint. We just got a new ICU, the place is beautiful.

So if she was already taking 40mg daily (30 if she had renal...but I doubt it as she was taking the tx dose q12)....and formed a clot...I do wonder what simply doubling it would do insofar as reducing risk...hmmm...oh...she got a pe...

 

[WVUPharm2007]

At this point, I think it's more for the attendings curiosity than anything else.

And at this point...I'd say genetics is my best guess...

 

[StaviZFingerZ]

Treatment dose is 1mg/kg SQ q12h unless renally compromised...

Hard to imagine she's only 40kg.. and she could as well be. But if not, it's possible she's underdosed.

 

[Praziquantel86]

So if she was already taking 40mg daily (30 if she had renal...but I doubt it as she was taking the tx dose q12)....and formed a clot...I do wonder what simply doubling it would do insofar as reducing risk...hmmm...

Good point. I'd be surprised that hasn't happened by tomorrow. Either that or she'll get put on Arixtra for some reason.

 

[WVUPharm2007]

Good point. I'd be surprised that hasn't happened by tomorrow. Either that or she'll get put on Arixtra for some reason.

I'd put her on a heparin drip. Obviously she has some sort of issue with lovenox not illiciting the proper response...try something else. Arixtra....maybe...I'd just go old school.

 

[Praziquantel86]

I think we'll probably end up just increasing the dose on the enoxaparin. I'll agree that it's probably genetic...my guess is that she has an undetected hypercoagulable state, which could cause both the pulmonary hypertension and the PE.

For what it's worth, a few of the recent studies I came across questioned the utility of anti-XA for measuring anticoagulation. Looks like the only strong correlation is increased bleeding risk with supratherapeutic levels.

 

[aboveliquidice]

So, we have a bit of an oddball case in our CCU right now. A mid-50s woman was transferred into our hospital after developing pulmonary hypertension and a subsequent PE. She's on Flolan running at about 17ng/min and bosentan. The PE is being treated with enoxaparin 40mg q12 (she's a pretty small woman).

We've been drawing anti-XA levels for the last few days, and each one comes back at about 0.1. The nurse says that the patients been tolerating the injections very well, and the MAR doesn't have any doses missed. We've also made sure that the lab hasn't screwed up.

I've been trying to figure out why the levels are still at pretty much baseline values even with therapeutic dosage. I can't find any literature out there, and any drug interactions would increase the bleeding risk. The attending says that she's seen similar things in pregnant women (she thinks it's hormonal changes in the coagulation cascade), but this patient is definitely not pregnant.

Any ideas?

Did you verify injection + 4 hours for appropriate level??? Our hospital was drawing them to soon - resulting in falsely low values. Lexi is reporting no specific range for DVT prophylaxis (it says it typically isn't drawn, but when it has it is <0.45 units / ml). That seems odd, considering Lovenox isn't dosed in units...

Our hospital almost never does Anti Xa levels... and when they do it has ended up being mishandled at some point in the process.

 

[Aznfarmerboi]

How much does anti 10x factor monitoring cost? I never really see them ordered for lmwh.

 

[bigpharmD]

I worked at a hospital that switched over to anti Xa monitoring and they only did because somehow they found it to be cheaper and more reliable

 

[Praziquantel86]

So, here's what ended up happening. The ICU attendings switched, and the new one didn't really care why the levels were so low. So the issue was dropped and she was switched to UFH.

They're thinking that the pulmonary hypertension and PE is either chronic coagulopathy or sarcoma. Evidently there's a procedure that a hospital in San Diego performs where they basically dissect the pulmonary vasculature and remove the thrombus in order to figure out the cause (don't know why it's just San Diego that does this). The patient hasn't agreed to being shipped across the country to have her lungs cut apart.

I'd still like to see if there are any other cases of virtually no response to LMWH out there, but as has been said before, it's probably some bizarre genetics at work.

 

[StaviZFingerZ]

heh,

that's what I said. Treat first, with UFH.....because UFH is titrated to therapeutic aPTT that coincides with therapeutic levels of anti factor Xa level between 0.3 - 0.7.

So, here's what ended up happening. The ICU attendings switched, and the new one didn't really care why the levels were so low. So the issue was dropped and she was switched to UFH.

They're thinking that the pulmonary hypertension and PE is either chronic coagulopathy or sarcoma. Evidently there's a procedure that a hospital in San Diego performs where they basically dissect the pulmonary vasculature and remove the thrombus in order to figure out the cause (don't know why it's just San Diego that does this). The patient hasn't agreed to being shipped across the country to have her lungs cut apart.

I'd still like to see if there are any other cases of virtually no response to LMWH out there, but as has been said before, it's probably some bizarre genetics at work.

 

[Praziquantel86]

heh,

that's what I said. Treat first, with UFH.....because UFH is titrated to therapeutic aPTT that coincides with therapeutic levels of anti factor Xa level between 0.3 - 0.7.

In general, what are your opinions on choosing between UFH and LMWH for treating a PE/DVT? When do you think it would be appropriate use LMWH as opposed to a heparin drip?

 

[WVUPharm2007]

In general, what are your opinions on choosing between UFH and LMWH for treating a PE/DVT? When do you think it would be appropriate use LMWH as opposed to a heparin drip?

Somewhere a Lovenox drug rep is preparing a pamphlet to give you about HIT...

 

[rphello]

Somewhere a Lovenox drug rep is preparing a pamphlet to give you about HIT...

Is that an Argatroban rep hot on his heels?

 

[Gosondth]

So, here's what ended up happening. The ICU attendings switched, and the new one didn't really care why the levels were so low. So the issue was dropped and she was switched to UFH.

They're thinking that the pulmonary hypertension and PE is either chronic coagulopathy or sarcoma. Evidently there's a procedure that a hospital in San Diego performs where they basically dissect the pulmonary vasculature and remove the thrombus in order to figure out the cause (don't know why it's just San Diego that does this). The patient hasn't agreed to being shipped across the country to have her lungs cut apart.

I'd still like to see if there are any other cases of virtually no response to LMWH out there, but as has been said before, it's probably some bizarre genetics at work.

UCSD Thornton hospital specializes in PH and pulmonary thrombectomies; they perform approximately 5 to 6 procedures a week with pretty good outcomes.