PTT-LA, Lupus Anticoagulant PTT
One 0.75 mL citrated Blue Top Tube (BTT) plasma aliquot.
If more than one coagulation test is ordered, a separate aliquot is needed for each test
-Collect in Citrated Blue Top Tube (BTT)
-Citrate anticoagulant must be adjusted for HCT >55%
-Tube must be at least 90% full
-Invert completely 3-4 times (without shaking) to mix
*See Instructions for: Preparation of Platelet Poor Plasma
Clotted or Hemolyzed sample
Contamination with IV or Hickman Line fluids
Specimens that thaw during storage or transport
To increase the sensitivity and specificity of the laboratory diagnosis of lupus anticoagulants (LA) both the DRVVT and the SCT should be ordered. These two tests have been combined as a Lupus Anticoagulant Panel (LAPAN) test order.
Lupus anticoagulant testing (DRVVT and SCT) should not be performed on patients receiving rivaroxaban, apixaban, dabigatran, or warfarin. For patients on these medications, one may consider anticardiolipin antibody and/or anti-beta-2 glycoprotein 1 antibody testing.
See Lab Clinical Practice Guidlines for more
SCT ratio: <=1.16 Negative for LA
SCT ratio: >1.6 Positive for LA