ADAMTS-13 Activity with Reflex Inhibitor, Plasma
Test Overview
Clinical Utility
This test has not yet been approved by Health Canada. This test was validated by the special coagulation laboratory at St. Michael’s Hospital and is therefore considered a laboratory-developed test (LDT). Result must be interpreted within the clinical context.
ADAMT-13 Inhibitor will only be tested (and billed) when if Activity level is 10% or less.
Thrombotic Thrombocytopenic Purpura (TTP) is generally associated with a severe deficiency (i.e. < 10%) ADAMTS-13 activity. TTP may be primary (Upshaw-Schulman Syndrome) or secondary (acquired) and this assay does not distinguish between these two forms. The diagnosis of TTP should not be based solely on the ADAMTS-13 activity.
Patients with other thrombotic microangiopathies (e.g. Atypical Hemolytic Uremic Syndrome (aHUS), Hemolytic Uremic Syndrome (HUS), Disseminated Intravascular Coagulation (DIC)) or other conditions (sepsis, malignant hypertension, etc.) may have reduced ADAMTS-13 activity. However, ADAMTS-13 activity of 10% or lower is highly suggestive of TTP.
Of note: Transfusion of plasma or apheresis with plasma prior to sample collection may mask deficiency. Collect specimen prior to transfusion of any components and prior to apheresis. Collect specimen prior to transfusion of any components and prior to apheresis.
NOTE: To convert U/mL to percentage, % = U/mL x 100
Method
Enzyme-linked immunosorbent assay (ELISA)
Result Included
ADAMTS-13 Activity; ADAMTS-13 Inhibitor
Aliases/Synonyms
von Willebrand factor-cleaving protease (VWFCP); ADAMTS13; ADAMTS 13
Specimen
Specimen Type
Plasma (Sodium Citrate)You must submit a completed ADAMTS-13 Requisition with the specimen.
Volume
Sample Volume
2 x 1 mL
Patient Preparation
Collect specimen prior to transfusion of any components and prior to apheresis.
Collection & Handling
Collection Instructions
Ensure full draw with 9:1 ratio (9 parts blood to 1 part anticoagulant).
Handling Information
Prepare platelet-poor plasma and divide into two 1 mL aliquots. Freeze immediately. Store and send frozen.
Stability
| Ambient | Refrigerated | Frozen |
|---|---|---|
| 4 hours | Unacceptable | 14 days |
Stable up to six months at -70C<br>
Rejection Criteria
| Criteria | Specification |
|---|---|
| Specimen | Not frozen |
| Hemolysis | Gross |
Performance & Interpretation
Turnaround Time
15 days
Results
-
ADAMTS-13 ActivityU/mLNormal: >0.40
Decreased: 0.10 - 0.40
Very Low: <0.10 -
ADAMTS-13 InhibitorU/mLPositive: >15
Borderline: 12 - 15
Negative: <12
Comment
Thrombotic Thrombocytopenic Purpura (TTP) is generally associated with a severe deficiency (i.e. ^lt;10%) ADAMTS-13 activity. TTP may be primary (Upshaw-Schulman Syndrome) or secondary (acquired) and this assay does not distinguish between these two forms. The diagnosis of TTP should not be based solely on the ADAMTS-13 activity.
Patients with other thrombotic microangiopathies (e.g. Atypical Hemolytic Uremic Syndrome (aHUS), Hemolytic Uremic Syndrome (HUS), Disseminated Intravascular Coagulation (DIC)) or other conditions (sepsis, malignant hypertension, etc.) may have reduced ADAMTS-13 activity. However, ADAMTS-13 activity of 10% or lower is highly suggestive of TTP.
Of note: Transfusion of plasma or apheresis with plasma prior to sample collection may mask deficiency. Collect specimen prior to transfusion of any components and prior to apheresis.Collect specimenprior to transfusion of any components and prior to apheresis.This test has not yet been approved by Health Canada.This test was validated by the special coagulation laboratoryat St. Michael's Hospital and is therefore considered alaboratory-developed test (LDT). Result must be interpretedwithin the clinical context.
NOTE: To convert U/mL to percentage, % = U/mL x 100
Referral Location
Canada
Interface & Setup
HL7 Interface Codes
| Order Code | Result Name | Result Codes | Units |
|---|---|---|---|
| ADAMR P | ADAMTS-13 Activity | 63123 | U/mL |
| ADAMTS13-Inhibitor | 63152 | U/mL |
Test Version
Last Updated
2023-12-22