D Dimer Test

[drabtshirt]

I have heard from several residents that d-dimer is not accurate in patients who have been in the hospital for longer than a few days, but not sure why.

Is this true? Do you know why?

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[RTrain]

AAGGHHHHH!!! I hate hate hate the d-dimer! Why must the ER order this lab on everyone with chest pain, SOB, hypoxia, tachycardia, or a hangnail, no matter their pre-test probability of venous thromboembolism???


Okay, now that I got that out of the way... D-dimer isn't likely to be helpful in a patient who has been hospitalized for several days because it is a very sensitive indicator of coagulation cascade activation, so by HD#2 a patient generally has several reasons for an elevated d-dimer just related to hospitalizations - e.g. invasive procedures, prolonged bedrest (part of Virchow's Triad), or even multiple phlebotomies.

 

[nattygann01]

AAGGHHHHH!!! I hate hate hate the d-dimer! Why must the ER order this lab on everyone with chest pain, SOB, hypoxia, tachycardia, or a hangnail, no matter their pre-test probability of venous thromboembolism???
quote]

In their defense, a D-dimer IS only used for those with a low pre-test probability, so I guess it would make sense to use it in those patients that you suspect probabily don't have a PE. I'd be more concerned if they were using it in a person with a high pre-test probability...but I do get your point...

 

[RTrain]

In their defense, a D-dimer IS only used for those with a low pre-test probability, so I guess it would make sense to use it in those patients that you suspect probabily don't have a PE. I'd be more concerned if they were using it in a person with a high pre-test probability...but I do get your point...

That's part of my complaint. They use it for everyone. 24 year old man with shortness of breath that started during his wedding? Better rule out PE with a d-dimer. thumbup 87 year old woman residing in a nursing home, with mechanical aortic valve, EF of 25%, cellulitis in her one remaining leg, with shortness of breath that started when she tripped over her O2 concentrator? Better rule out PE with a d-dimer. thumbdownthumbdown)

 

[DeLaughterDO]

That's part of my complaint. They use it for everyone. 24 year old man with shortness of breath that started during his wedding? Better rule out PE with a d-dimer. thumbup 87 year old woman residing in a nursing home, with mechanical aortic valve, EF of 25%, cellulitis in her one remaining leg, with shortness of breath that started when she tripped over her O2 concentrator? Better rule out PE with a d-dimer. thumbdownthumbdown)

Well, if they are using the D-dimer in the latter case, they need to be slapped across the face and taught a little about pre-test probability and the uselessness of a D-dimer in most cases.

I, personally, don't think the D-dimer is a great test in anyone over the age of 65 (except in very select cases of health 65 year-olds), because with the number of co-morbidities typically present in the elderly, it is a useless test and will need follow-up imaging anyway... provided their kidneys can handle the dye load. Unfortunately, the patient you described would most likely be admitted anyway for a syncope workup, or possibly to the trauma service for the head injury and facial fractures which she sustained after falling

BTW, this is a duplicate post. OP (original poster), we typically frown on this...

jd

 

[DeLaughterDO]

In their defense, a D-dimer IS only used for those with a low pre-test probability, so I guess it would make sense to use it in those patients that you suspect probabily don't have a PE. I'd be more concerned if they were using it in a person with a high pre-test probability...but I do get your point...[/QUOTE]

Agree

 

[HomerSD]

From the PIOPED investigators:
Stein et al. Diagnostic Pathways in Acute Pulmonary Embolism: Recommendations of the PIOPED II Investigators. Radiology 2007; 242(1):15-21

Note the d-dimer is helpful with a low or moderate pre-test suspicion of VTE.

 

[Hernandez]

Well, if they are using the D-dimer in the latter case, they need to be slapped across the face and taught a little about pre-test probability and the uselessness of a D-dimer in most cases.

jd

They also have never heard of the Pneumonia Outcome Research team and their fancy little thing called the Pneumonia severity index..

 

[CernerDrone]

The EM program at my school is awesome - they know their shiznit really well. They don't do such nonsense - so not every ER doc does that.

PERC protocol taught by my ED attending:

O2 sat > 95, HR < 100, age < 50, no trauma/surgery requiring hospitalization within the last 4 weeks, no estrogen use, no hemoptysis, no prior hx of venous thromboembolism, and no unilateral leg swelling.

Rules out PE pretty well if you fit all those criteria.

 

[Strength&Speed]

ddimers only helpful when its negative. and low prob of pe. that's it.

 

[Hernandez]

ddimers only helpful when its negative. and low prob of pe. that's it.

there is some (limited data) that says a D-dimer over 4000 has some positive predictive value for DVT/PE. but it is limited data. but we don't use that for a reason.

 

[DarthNeurology]

I have heard from several residents that d-dimer is not accurate in patients who have been in the hospital for longer than a few days, but not sure why.

Is this true? Do you know why?

I don't remember the source, but it is because d-dimer should be order when the patient arrives in the ED, i.e. to help differentiate SOB between PE vs. CHF versus other possible factors, because this is when it was shown in studies to have predictive value, I think the studies looking at inpatient evaluation did not show a usefullness for ruling out PE (or maybe there haven't been enough of these studies done), I postulate because there are so many things that can happen inpatient to elevate d-dimer, i.e. surgery, infection, so it is less useful in this population, but maybe no one really knows why. I do believe that a very large percentage of ICU patients, and a lesser extent of general medicine patients have a positive d-dimer without PE . . . so it is less useful. Somebody please post these article references as I can't find them and haven't read them in a while.

 

[RTrain]

I don't remember the source, but it is because d-dimer should be order when the patient arrives in the ED, i.e. to help differentiate between CHF versus other possible factors, because this is when it was shown in studies to have predictive value, I think the studies looking at inpatient evaluation did not show a usefullness for ruling out PE (or maybe there haven't been enough of these studies done), I postulate because there are so many things that can happen inpatient to elevate d-dimer, i.e. surgery, infection, so it is less useful in this population, but maybe no one really knows why. I do believe that a very large percentage of ICU patients, and a lesser extent of general medicine patients have a positive d-dimer without PE . . . so it is less useful. Somebody please post these article references as I can't find them and haven't read them in a while.

I assume you're thinking of PIOPED and PERC, and they've already been mentioned specifically in this thread. And d-dimer has nothing to do with CHF.

 

[Strength&Speed]

I don't remember the source, but it is because d-dimer should be order when the patient arrives in the ED, i.e. to help differentiate between CHF versus other possible factors, because this is when it was shown in studies to have predictive value, I think the studies looking at inpatient evaluation did not show a usefullness for ruling out PE (or maybe there haven't been enough of these studies done), I postulate because there are so many things that can happen inpatient to elevate d-dimer, i.e. surgery, infection, so it is less useful in this population, but maybe no one really knows why. I do believe that a very large percentage of ICU patients, and a lesser extent of general medicine patients have a positive d-dimer without PE . . . so it is less useful. Somebody please post these article references as I can't find them and haven't read them in a while.

i would assume that ddimers are more frequent in hospitalized patients due to increased bed time...increased stasis and minor coagulation (think Virchow's triad) as well as instrumentation, sickness, etc...all of which can increase a ddimer.

ddimers are not used for chf

ddimers to me are really of limited clinical usefulness...as was mentioned by multiple people before...it seems to only be truly helpful to exclude a pe/dvt as it is quite sensitive and any amount of thrombosis will cause it to be elevated.

 

[DarthNeurology]

ddimers are not used for chf

What I meant was in a patient who has SOB to differentiate that symptom, i.e. it looks like CHF, he/she is low risk for PE, lets do the d-dimer so we can rule that out, sorry poor grammar