ADAMTS 13 Inhibitor

Also Known as (Alias) ATS-13 inhibitor
Indications TTP
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

Spin within 4 hours and freeze plasma at -20C then ship frozen specimen on dry ice

Send samples to:
Bloodworks Northwest
Attn:  Platelet Immunology Lab, Rm 619
921 Terry Avenue
Seattle, WA 98104

For additional information please see Ordering Information

Requisition Form RFT- Immunogenetics/HLA and Platelet Immunology Labs
RFT Hemostasis Reference Laboratory
Transaction Code 3260-02
CPT Codes 85335
Test Schedule reflexive
Turn around Time (analytic time) 2-3 business days
Report/Results Fax number required to receive report