ADAMTS 13 Inhibitor (test performed if activity level <30%)
|Also Known as (Alias)||ATS-13 Inhibitor|
|Method||Flourescence Resonance Transfer Assay (FRET)|
|Test Information||If ADAMTS13 activity is less than 30%, then reflex testing for an inhibitor and antibody will be performed. The FRET assay is repeated using a 1:1 mix of normal pooled plasma and heat inactivated patient’s plasma. If the activity results are below the expect activity then the results are reported as a percent inhibition. Inhibition results of greater than 32% is considered positive in our assay.|
|Additional Test Information||Strong antibody-mediated inhibition of ADAMTS13 activity (>90%) is seen in approximately half of the patients with acquired TTP. The presence of this level of inhibition strengthens the case for a diagnosis of TTP. The significance of milder ADAMTS13 inhibition is unclear, particularly when the overall ADAMTS13 level is not severely depressed. The assay used does not distinguish between antibody-mediated and non-specific ADAMTS13 inhibition.
Caution should be exercised in the interpretation of any assay for ADAMTS13; the results should only be considered in the conjunction with the patient’s clinical condition. Previous transfusion, plasma infusion, plasma exchange, or free hemoglobin in the plasma (>2g/L) may affect the level of ADAMTS13 as well as any inhibitors that are present.
|Sample Requirements||Citrate (blue top)|
|Requested Volume||5cc Citrate (blue top)|
|Shipping Information||Ship to Bloodworks immediately after draw to ensure the laboratory receives specimen within 4 hours of draw time. If this is not possible, spin within 4 hours and freeze plasma at -20C, then ship frozen specimen on dry ice.
NOTE: If the sample is received as whole blood after 4 hours of draw time, the sample will need to be redrawn
Send samples to:
For additional information, please see Ordering Information
|Requisition Form||RFT- Platelet Immunology Laboratory
RFT- Hemostasis Reference Laboratory
|Turn around Time (analytic time)||2-3 business days|
|Report/Results||Fax number required to receive report|