Here are the results for our 12/11/08 quick question, "What assay do you use to detect abnormalities in fibrinolysis such as DIC?

Here is a response from Dr. John Olson differentiating the D-dimer reference interval from the venous thromboembolism (VTE) exclusion threshold. Dr. Olson responded to my question sent last week, excerpted here:

Dr. Olson, I hope all is well with you. I am having trouble answering Kim Kinney's question, and it brings me back to your D-dimer post from last summer. Ms. Kinney has a locally established reference interval, 110-290 D-dimer units,and a limit she uses to exclude VTE in the ED, 230 D-dimer units. Here at UAB we publish a normal range of 110 to 240 ng/mL but a PE/DVT exclusion limit of 500 ng/mL. Others establish a normal range and just use the upper limit of normal as the exclusion cutoff. What is CAP looking for when requesting a normal range and a separate VTE cutoff?

Dr. Olson's answer...

A D-dimer question from Kim Kinney at Clarian:

Hi George,

D-dimers! How do other participants handle the CAP question requiring not only the cut-off for D-dimer in your patient report but also the reference range?  Currently, we include our cut off in an interpretation that is tagged on every dimer we validate.

Our ED docs only want to look for a color change in the computer system on any analyte to notify the clinician of an "out of reference range" result.  Our reference range and our cut off are not the same! We are struggling with our computer piece to support the ED docs. How do others handle this? As always, thanks for the help.

I am trying to discontinue the fibrin (ogen) degradation products (FDP) assay in favor of the D-dimer.  I have read and used several of the posts here as references and reasons for this decision.  A recent question from an ER physician has me doing some further research and I need your help.  What about snake bites?  Many text recommend the FDP along with the routine PT, PTT and Fibrinogen.  Will the D-dimer serve the same purpose in this situation? Joe Lamb

Thank you for your question, Joe. The short answer is yes, but there is some disagreement on this issue, so I'll go into more detail.

At our institution we currently offer a quantitative D-dimer using the Sysmex CA-1500, and a fibrin degredation products assay (FDP, Remel Thrombo-Wellco Test).  What can I say to our physicians to convince them to allow us to stop offering the FDP, and to rely on the D-dimer (along with the platelet count, PT, PTT and fibrinogen) in the evaluation of DIC? Thank you for your time. Nicole Frantti

On Thursday, February 21, 2008, Colleen Marinucci from Elmendorf AFB wrote:

We perform the SimpliRED® qualitative d-dimer assay (AGEN Biomedical Ltd,  Brisbane, Queensland, Australia, distributed in the USA by American Diagnostica, Inc, Stamford, CT). Our internal med docs wondered why a patient with a small pulmonary embolism tested negative. This patient has, among other problems; pancreatitis, pulmonary hypertension, COPD and lupus anticoagulant. We have investigated the quantitative D-dimer on the Stratus and ACL 9000 but do not have access to ELISA. Any suggestions for improving our d-dimer dilemma? Thanks

Ms. Denise Broadbent, Laboratory Supervisor at Klickitat Valley Hospital in  Goldendale WA posted a question to Medlab-L I will summarize here, followed by a clear discussion from Warren Coffin of Crozer Keystone Health System:

 

Recently we ran a D-dimer, getting a result of >700 ng/mL (negative <230, normal up to 255 ng/ml).  The patient was transferred to another facility whose D-dimer result using a different system was 1.90 mg/L (negative <1.0, normal up to 2.6mg/l).  Understandably our ER doctor was concerned and has asked me to look into the matter.  Specimens were drawn the same day, several hours apart.  I and the hematology supervisor at the other facility have reviewed our QC records and repeated the specimens. Everything is fine except we called the D-dimer positive and the second facility called it suspicious.  I am aware of  the differences among instrumentation, reagents and methods, but, has anyone else seen a discrepancy like this before?