Sign in →

Test Code ADAM13 ADAMTS13 Activity and IgG Ab w/ Reflex to Inhibitor

Clinical Information

Thrombotic Thrombocytopenic Purpura (TTP) is a thrombotic microangiopathy that frequently leads to devastating thrombotic complications and sometimes death. ADAMTS13 protease deficiency is a primary risk factor in pathogenesis of TTP. An ADAMTS13 activity result of <10% can confirm a diagnosis of TTP. Anti-ADAMTS13 IgG antibodies inhibit ADAMTS13 activity. This test can be used to help differentiate between congenital and acquired TTP when coupled with an ADAMTS13 activity assay.

Synonym

  • AD13A
  • AD13IGG
  • von Willebrand Factor Cleaving Protease
  • Anti-ADAMTS13 antibodies

Profile Information

Reporting Name Available Separately Always Reported
ADAMTS13 Activity No Yes
ADAMTS13 IgG Antibody No Yes

Specimen Required

Acceptable Container/Tube: 3.2% Citrate Blue Top
Specimen Volume: 0.5 mL platelet poor plasma
Specimen Minimum Volume: 0.5 mL platelet poor plasma
Processing instructions: Do not refrigerate blood. Ensure tube is filled to the line. Within 2 hours of collection, process into platelet poor plasma. Follow CLSI Guideline H21 for processing platelet poor plasma. Transfer plasma to plastic tube. FREEZE IMMEDIATELY at -20°C or below. Ship frozen on dry ice.

Specimen Stability Information

Ambient: Whole blood must be processed into plasma and frozen within 2 hours from collection.

Frozen: 4 weeks at -20°C or below

Rejected Due To

  • Clotted specimens
  • Underfilled or overfilled tube

Testing Algorithm

Inhibitor titer test (LAB1006) reflexes if ADAMTS13 activity is <30% and patient has not had a high inhibitor result in the past. Once a patient has a high inhibitor result (0.5 BU or higher), inhibitor testing will no longer be performed on future samples for that patient. Patients who are confirmed to have congenital TTP will not have inhibitor titer testing performed.

Samples that reflex for inhibitor titer test will be sent to ARUP for testing at an additional charge.

Reflex Tests

Reporting Name Available Separately Always Reported
ADAMTS13 Inhibitor No No

Reference Values

ADAMTS13 Activity
≥40 %

 

ADAMTS13 IgG Antibody
≤12.0 U/mL

Cautions

ADAMTS13 Activity: Mild to moderate deficiencies of ADAMTS13 of unclear clinical significance have also been observed in other clinical conditions, such as atypical hemolytic uremic syndrome (aHUS), sepsis, disseminated intravascular coagulation, and metastatic malignancy.


ADAMTS13 IgG Antibodies: Samples with high concentrations of autoantibodies other than anti-ADAMTS13 may result in weak positive or borderline results. Elevated bilirubin levels may cause a negative interference with anti-ADAMTS13 IgG antibodies test results.  

Method Description

Technozym enzyme-linked immunosorbent assay (ELISA) 

Performing Lab

Clinical Lab UH

Day(s) Performed

Monday through Friday (excludes OSU holidays)

Report Available

ADAMTS13 activity: 3 to 5 days

ADAMTS13 IgG antibodies: 5 to 7 days

Reporting Name

ADAMTS13 Activity
ADAMTS13 IgG Antibody

CPT Code Information

85397
83520

LOINC Code Information

53622-7
40824-5