Should all Coagulation Specimens be PPP?
At the Mayo Medical Laboratories Coagulation Testing Quality conference in Minneapolis, April 14–17, Dr. Dorothy Adcock Funk of Esoterix reported on the 2008 revision of Clinical and Laboratory Standards Institute (CLSI) Standard H21-A5, Collection, Transport, and Processing of Blood Specimens for Testing Plasma-Based Coagulation Assays and Molecular Hemostasis Assays. One interesting comment she made is that it is not necessary to prepare platelet-poor plasma (PPP; plasma with a platelet count less than 10,000/uL) for routine coagulation testing on fresh plasma. She reconfirmed, however, that plasmas for freezing and lupus anticoagulant (LA) testing must be PPP. Bioactive platelet granule materials are released upon freezing, including platelet factor 4 (PF4), which neutralizes heparin. In LA testing, platelets provide high concentrations of membrane phospholipid, which may neutralize low-titer LAs.
At UAB we centrifuge all our coagulation specimens, routine and special, at 2000g for 15 minutes, producing PPP in a single spin. Dr. Larry Brace at Edwards Hospital, Naperville, IL, double-spins all specimens using the Stat-spin Express centrifuge. Our reasoning is that even though it isn’t necessary to prepare PPP for routine tests, our laboratory staff often get calls for special add-ons using existing specimens. Further, we may choose to reflex unexpectedly prolonged partial thromboplastin time (PTT) assays to our LA profile.
I’d like to know what you do about PPP preparation; all specimens, or just those for freezing and LA profiles? Please answer by providing your comments below. Geo.
I’d like to know what you do about PPP preparation; all specimens, or just those for freezing and LA profiles? Please answer by providing your comments below. Geo.
