Plasma

Must include the following information:

• Patient identifiers (full name, date of birth, sex and medical record number)
• Pertinent history and clinical findings
• Date of collection & sample type
• Ordering physician

Preferred Minimum: 1 mL frozen citrated plasma
Absolute Minimum: 0.5 mL frozen citrated plasma

If samples do not arrive in the reference laboratory labeled (patient name, patient date of birth and sample type) and frozen after processing immediately, they will be rejected for testing.

Deliver to laboratory immediately after collection. Critical frozen. Samples accepted Monday-Friday

Monday - Friday ONLY (No weekend or holiday service).

For same day Activity level service, sample must be collected by 12 noon and in the lab by 1pm.

24 business hours upon receipt at reference laboratory (upon receipt in laboratory)

Activity
Normal (>60IU/dL); Reduced (10IU/dL-60IU/dL; Depleted (<10IU/dL)
Inhibitor
<=0.4 U

Comments:
If Activity is <25IU/dL inhibitor test will be performed next business day. Additional charges apply.

If activity level only is necessary for testing, please order LAB8450 - MORL ADAMTS-13 Activity.

Inhibitor only is no longer available.

Limits of testing methodology: The assay utilizes short vWF peptide as substrate which lacks exosites for ADAMTS-13 interaction.

Thrombotic thrombocytopenic purpura:
Thrombotic thrombocytopenic purpura (TTP) is an ultra-rare disease caused by platelet clumping on aggregated unusually large von Willebrand factor (vWF) multimers, leading to microthrombi formation in small blood vessels and potentially culminating in multi-organ failure. In healthy individuals, ADAMTS13, a circulating protease, specifically cleaves large vWF multimers, significantly reducing platelet thrombi formation under high shear stress. Reduced ADAMTS13 activity (<60%) can be found in the acquired form of TTP in association with ADAMTS13 autoantibodies. ADAMTS13 activity is totally absent (<10%) in the inherited form of TTP, which is known as Upshaw- Schülman syndrome.

Atypical hemolytic uremic syndrome:
Atypical hemolytic uremic syndrome (aHUS) is another ultra-rare thrombotic microangiopathy. Although ~50% of cases of aHUS are caused by mutations in genes in the alternative complement pathway, about 60% of aHUS patients are estimated to have reduced ADAMTS13 activity (<60% of normal but above 10% of normal) (1). Whether reduced ADAMTS13 activity is an important component of the aHUS phenotype has not been determined.

Indications for screening: Screening is appropriate for patients with TTP and aHUS.

Reference:
Feng S, et al.: Partial ADAMTS13 deficiency in atypical hemolytic uremic syndrome. Blood. 2013 Aug 22;122(8):1487-93. Epub 2013 Jul 11.

Fluorescence Resonance Energy Transfer (FRET)

85335, 85397

See also:
MORL ADAMTS-13 Activity, Plasma