MORL ADAMTS-13 Inhibitor Only
Label Mnemonic: MADAMIN
Epic Lab Code: LAB8451
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Plasma
Collection Medium:
Light Blue top tube 2.7 mL (Na Citrate)
Minimum:
Preferred Minimum: 1 mL frozen citrated plasma
Absolute Minimum: 0.5 mL frozen citrated plasma
Delivery Instructions:
Deliver to laboratory immediately after collection. Critical frozen.
Testing Schedule:
Testing performed Monday - Friday ONLY (No weekend or holiday service)
Turn Around Time:
24 hours upon receipt at reference laboratory
NOTE: For same day service sample must be collected by 7:00 am.
Reference Range:
<=0.4 U
Interpretive Data:
Limits of testing methodology: The assay utilizes short vWF peptide as substrate which lacks exosites for ADAMTS-13 interaction.
Comments:
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.
Methodology:
Fluorescence Resonance Energy Transfer (FRET)
CPT Code:
85335