ADAMTS 13 Inhibitor (test performed if activity level <30%)
| 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 | 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 |
| 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 |
