General Information

UPHSM LIS Test #: 3934
Schedule: Varies, Monday - Friday
Testing Time: 7 - 10 days
Testing Lab: Mayo Labs

Specimen Info
Only 1 specimen type required, unless otherwise specified

Volume: 2 mL in 2 plastic vials each containing 1 mL
Temperature: Frozen
Tube Type: 1 Blue Top (Citrate)
Collection Info:
1. Specimen must be drawn prior to replacement therapy.
2. Spin down, remove plasma, spin plasma again, and remove from button.
3. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or, ideally, < or =-40 degrees C.

Additional Information:
1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. If priority specimen, mark request form, give reason, and request a call-back.
3. Each coagulation assay requested should have its own vial.


Fluorescent Resonance Energy Transfer (FRET)

CPT Codes

85397/ ADAMTS13 activity assay
85335/ ADAMTS13 inhibitor screen assay (if appropriate)
85335/ ADAMTS13 Bethesda titer (if appropriate)

The following test(s) may be added per the testing algorithm:
Mayo ADMIS "ADAMTS13 Inhibitor Screen"
Mayo ADMBU "ADAMTS13 Inhibitor Bethesda Titer"

* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding
is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Reference Range

ADAMTS13 Activity Assay: >= 70%
ADAMTS13 Inhibitor Screen: NEGATIVE
ADAMTS13 Bethesda Titer: <0.4 BU

Interpretive Comments: <10% ADAMTS13 activity is highly indicative of thrombotic thrombocytopenic purpura (TTP) in an appropriate clinical setting. The presence of ADAMTS13 inhibition (positive inhibitor screen) with a measurable antibody titer is most consistent with an acquired TTP.