Assisting with the diagnosis of immune or acquired thrombotic thrombocytopenic purpura

Fasting preferred

Specimen must be collected prior to replacement therapy

To obtain adequate sample volume please collect 2 tubes:

Lt blue Sodium citrate (Na Cit) - 2.7mL 

• Do not over or under fill tube as the ratio of anticoagulant to whole blood is critical

Coag – tube fill guidelines

• Immediately following collection, mix sample thoroughly by gently inverting 8 - 10 times to prevent clotting

1. Centrifuge 
2. Transfer plasma into a plastic vial 
3. Centrifuge a second time
4. Aliquot plasma (one mL per aliquot) into two seperate screw cap transfer vial/tube (Mayo T914), leaving 0.25 mL in the bottom of the centrifuged vial
5. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or, ideally, below -40 degrees C.

Screw cap transfer vial/tube (Mayo T914) x2

Frozen (strict) 

Refrigerated - NO

Ambient - NO

Fluorescence Resonance Energy Transfer (FRET)

ADAMTS13 ACTIVITY ASSAY: > or =70%

ADAMTS13 INHIBITOR TITER: <0.5 BU

Less than 10% ADAMTS13 activity is highly indicative of thrombotic thrombocytopenic purpura (TTP) in an appropriate clinical setting. The presence of ADAMTS13 measurable Bethesda titer is most consistent with an acquired (autoimmune) TTP.