From Barbara Caufield, Good Samaritan Hospital: We adjust the Na citrate volumes in coagulation tubes when the hematocrit (HCT) is > 55%. Do you recommend correcting for low HCTs? Can you tell me what formula you would use for a low HCT? At what HCT percentage do you recommend adjusting the sodium citrate? Thank you!
Category: Specimen Management
I am trying to find a chart or article that tells how long plasma is good for hemostasis testing. The question has arisen about fresh samples and frozen samples. We often get requests for add-on tests and need to know how long is too long. Do you know of a resource that will provide this information? Thanks, Deborah Whetzel MT(ASCP), CLS Supervisor, Children’s Hospital of the King’s Daughters.
Originally posted October 25, 2011:
From Kim Kinney at Indiana University (formerly Clarian) Health Center:
Hi George, Even though I am not in coag much any more I still get a ton of questions. One of our TC’s was questioning our storage of PT/INR specimens. We follow the current recommendations of room temperature for 24 hours. We do not accept refrigerated whole blood or spun plasma refrigerated. We do accept frozen plasma. He wanted to know why you can freeze plasma without activation of VII but refrigeration may activate VII and therefore, shorten your PT. I was not sure of an answer other than frozen is a quick freeze. Can you help?
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Here is a question originally posted November 4, 2011 that did not attract discussion at the time:
I received a note from David Chance, Good Samaritan Medical Center, Corvallis OR, commenting that, unlike underfilled coagulation specimen (blue-closure) tubes; overfilling tubes, unless clots are present, does not affect coagulation results. Overfilling may occur when a specimen is collected by syringe and pushed into a tube. There is no comment on overfilling in CLSI H21-A5, however I suspect that many laboratories reject obviously overfilled tubes. Please comment on this, what is your policy on overfilled tubes?
Actually, nothing on this site is the last word, however I contacted Dennis J. Ernst, MT (ASCP), Center for Phlebotomy Education, about Donna Kaiser’s 4/5/13 acid-citrate-dextrose (ACD) tube question. Dennis’s response is: “Nice to hear from you. I haven’t heard anything about the use of ACD tubes in this context. I wonder if a tube manufacturer would shed light on it. It would be interesting to hear what the coag folks at BD would say.”
From Donna Kaiser, St. Joseph Health System: I was wondering if you have any information on using acid citrate dextrose (ACD) tubes for EDTA platelet clumpers. I have heard they may work better than the sodium citrate tubes especially for oncology patients. If so, are Sol A or Sol B tubes being used and is there a dilution factor. Thanks.
From Barbara Robinson, MT (ASCP), Children’s Hospital of New Orleans, If a sample is tested for D-dimer, prothrombin time (PT) and partial thromboplastin time (aPTT, PTT), and the anticoagulant in tube has not been adjusted for high hematocrit (HCT = 60.8%), what tests would be invalid, and how would results be affected?