ADAMTS13 Activity with Reflex to Inhibitor

VWF Cleaving Protease Activity, Protease Activity Inhibitor for TTP

Test Codes

EPIC: LAB1232266, Beaker: ADAMSTSAct, Quest: 14532

NOTE: If the ADAMTS13 Activity result is ≤0.30 IU/mL, then ADAMTS13 Inhibitor will be performed at an additional charge (CPT: 85335).

Department

Send Outs

Specimen Collection Criteria

Collect: One Light Blue-top Sodium Citrate tube, mix gently 3-4 times.

Physician Office/Draw Specimen Preparation

Centrifuge 15 minutes at 1500 g within one hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Freeze (-20°C/-4°F or below) immediately.

Preparation for Courier Transport

Transport: 1.0 mL platelet poor plasma (PPP) pourover, frozen (-20°C/-4°F or below). (Minimum: 0.5 mL)

Rejection Criteria

• Gross hemolysis.
• Grossly lipemic.
• Grossly icteric.
• Specimens collected in EDTA.
• Specimens not collected and processed as indicated.

In-Lab Processing

Centrifuge 15 minutes at 1500 g within one hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Freeze  (-20°C/-4°F or below) immediately.

Transport: 1.0 mL platelet poor plasma (PPP) pourover, frozen (-20°C/-4°F or below). (Minimum: 0.5 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): unacceptable
Refrigerated (2-8°C or 36-46°F): unacceptable
Frozen (-20°C/-4°F or below): 21 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Monday – Saturday.
Results available in 2-4 days.

Reference Range

ADAMTS13 Activity:	0.68-1.63 IU/mL
ADAMTS13 Inhibitor:	<0.4 BEU

Test Methodology

Immunoassay (IA)

Clinical Utility

ADAMTS13 Activity with Reflex to Inhibitor – ADAMTS-13 is a zinc metalloprotease that cleaves ultra large vWF multimers. Studies have shown that low levels of ADAMTS-13 activity are associated with thrombotic thrombocytopenic purpura (TTP), a life-threatening hematological condition characterized by a low platelet count, microvascular thrombi, red cell fragmentation, and renal complications. Congenital TTP is a rare inherited disease caused by mutations within the ADAMTS-13 gene, which result in the production of non-functional protein. The acquired form of TTP is an autoimmune-like disorder caused by the development of autoantibodies to ADAMTS-13 that inhibits enzyme activity.

NOTE: In the FDA approved test used at Quest Diagnostics, results are reported using international units (IU) per mL and not in percent (%), typically described in many studies. To convert to %, multiply IU/mL by 100%. For example, 0.3 IU/mL would be equivalent to 30% (0.3 IU/mL x 100%).

CPT Codes

85397, 85335 (if appropriate), 85335 (if appropriate).

Contacts

Last Updated

12/17/2025