ADAMTS13 Activity
| Order Code: | ADAMTS13 |
| Epic Lab Code: | LAB2539 |
| Order Form: | A-1a Miscellaneous Request or Epic Req |
Commercial Mail-out Laboratory
6240 RCP
356-3527
6240 RCP
356-3527
Specimen:
Platelet-Poor Plasma
Collection Medium:
 |
| Light Blue top tube 2.7 mL (Na Citrate) |
Minimum:
Preferred Minimum: THREE aliquots (0.5 mL each)
Absolute Adult/Pediatric Minimum: TWO aliquots (0.4 mL each)
Analytic Time:
ADAMTS13 activity and inhibitor assays are run daily, Monday - Friday.
Turnaround time is 2-4 days upon receipt at reference laboratory.
ADAMTS13 antibody assay is run weekly. Turnaround time is 7-10 days upon receipt at reference laboratory.
ADAMTS13 antibody assay is run weekly. Turnaround time is 7-10 days upon receipt at reference laboratory.
Reference Range:
ADAMTS13 Activity > 67%
ADAMTS13 Inhibitor < 0.4 Inhibitor Units
ADAMTS13 Antibody < 18 Arbitrary Units
ADAMTS13 Inhibitor < 0.4 Inhibitor Units
ADAMTS13 Antibody < 18 Arbitrary Units
Interpretive Data:
Microtiter plates coated with monoclonal anti-ADAMTS13 antibody are
used to measure ADAMTS13 activity by Fluorescence Resonance Energy
Transfer (FRET).
ADAMTS13 levels of less than 5% may be associated with either inherited
(Upshaw-Schulman Syndrome) or acquired thrombotic thrombocytopenic
purpura (TTP).
A variety of medical conditions may result in a mild to moderate
deficiency of ADAMTS13 activity. Recent plasma exchange therapy may
raise the observed ADAMTS13 activity.
The monoclonal anti-ADAMTS13 antibody is directed against the CUB
domain; therefore, certain forms of ADAMTS13 (with mutations in the CUB
domains) may not be equivalently measured due to reduced binding to the
antibody.
Comments:
ADAMTS13 Evaluation is a reflexive testing algorithm. Activity is
always performed. If activity result is <= 30%, the inhibitor assay
will be performed. If inhibitor result is <= 0.7 Inhibitor Units, the
antibody assay will be performed.
Please print, complete and submit the Hemostasis Test Requisition to the lab, with the specimen and the Epic Requisition.
Please print, complete and submit the Hemostasis Test Requisition to the lab, with the specimen and the Epic Requisition.
Test
Limitations:
Not all patients with idiopathic TTP have abnormal ADAMTS13 laboratory
results. The reported prevalence of severe deficiency in patients
presenting with idiopathic TTP varies from 33 to 100%. Prevalence of
inhibitors ranges from 44% to 93% with a somewhat higher reported
prevalence of antibody detected by ELISA.
Severe deficiency of ADAMTS13 has been proposed as a relatively specific laboratory marker of TTP. Whether severe deficiency occurs in other conditions is debated. Mild to moderate deficiency has been observed in multiple medical conditions including inflammation, hepatic dysfunction and pregnancy.
Recent plasma exchange therapy may affect ADAMTS13 assay findings.
Hemolysis with plasma free hemoglobin > 2 gm/L or an elevated bilirubin level can cause artifactually low ADAMTS13 activity and false positive inhibitor results.
ADAMTS13 Antibody assay is less specific than the functional inhibitor assay, and positive results have been observed in people without severe ADAMTS13 deficiency, including healthy individuals and patients with other immunologic disorders.
Severe deficiency of ADAMTS13 has been proposed as a relatively specific laboratory marker of TTP. Whether severe deficiency occurs in other conditions is debated. Mild to moderate deficiency has been observed in multiple medical conditions including inflammation, hepatic dysfunction and pregnancy.
Recent plasma exchange therapy may affect ADAMTS13 assay findings.
Hemolysis with plasma free hemoglobin > 2 gm/L or an elevated bilirubin level can cause artifactually low ADAMTS13 activity and false positive inhibitor results.
ADAMTS13 Antibody assay is less specific than the functional inhibitor assay, and positive results have been observed in people without severe ADAMTS13 deficiency, including healthy individuals and patients with other immunologic disorders.
Methodology:
Fluorescence Resonance Energy Transfer (FRET)-Based Kinetic Assay
CPT Code:
85397, 85335 (if inhibitor is performed), 83520 (if antibody is
performed)