Register Login

Controls and Heparin in Mixing Studies

George: We recently had a CAP inspection and had a couple of recommendations that we’re trying to tidy up.

1.  HEM 37991 regarding a control for PT mixing studies. We were using what we considered to be the normal control but were told to order the Dade Control N. I’ve ordered and just want to make sure that the control contains normal levels of each factor. I’m hoping the package insert will provide me with the documentation but just off the top of your head, is it an acceptable control?

2.  HEM 38002 regarding documentation showing the procedure either includes a process to detect heparin or other antithrombotic drugs OR does the patient report include a comment that the effect of inhibitor drugs cannot be excluded. Can you share a mixing study procedure that would include that verbiage?  We don’t include a process to detect heparin as we just do a quick mix patient with control and see if corrects.   Anything more complicated gets sent out. Thanks, George.

Joanne Kendrick, MT(ASCP)
Core Lab Supervisor
LabCorp at Brookwood Medical Center
Birmingham, AL

Hello, Joanne (and also Rita). Glad to take a question from here at home and I hope things are good at Brookwood.

The first recommendation is…
HEM.37991 When plasma-mixing studies are performed, is an appropriate pooled plasma utilized?

Yes, the Dade Control N is appropriate for a mixing study as are its competitors Precision BioLogic Cryocheck Pooled Normal Plasma or Stago’s STA Coag-control N. The material should be a pool of at least 20 screened male and female normal donors between 18 and 66.

For the second recommendation…
HEM 38002:  For samples with positive mixing study results, is there either a procedure to detect heparin or other antithrombotic drugs that inhibit coagulation, or is the result reported with a comment that the effect of inhibitor drugs cannot be excluded?

For this one, you may wish to simply add a thrombin time to your assays, as it is simple and cheap to maintain and perform. If not, you may wish to add a phrase such as this:

“Prothrombin and partial thromboplastin times may be prolonged by the presence of unreported heparin, argatroban, or bivalirudin. The presence of one of these anticoagulants could not be ruled out.”

Comments (0)

No comments here.

Leave a Reply