ADAMTS-13 testing

ADAMTS-13 Activity and Antibody testing is now being offered in NSW by the haematology department at Hunter Area Pathology Service (HAPS).

ADAMTS-13 and TTP?

ADAMTS-13 (A Disintegrin And Metalloprotease with ThromboSpondin repeats member #13) is the major protease responsible for cleaving von Willebrand factor (vWF) and, as such, is responsible for control of vWF multimer length. In TTP, a severe deficiency of ADAMTS-13 activity, (<10% of normal plasma) causes accumulation of ultra-large vWF multimers which in turn leads to formation of platelet-rich thrombi in the microcirculation and to symptoms of end-organ ischaemia.  

Deficiency of ADAMTS-13 is most commonly acquired (i.e. caused by inhibitory auto-antibodies directed against ADAMTS-13) and less commonly, congenital (i.e. caused by production of a dysfunctional ADAMTS-13 protein). Measurement of ADAMTS-13 and detection of ADAMTS-13 specific antibodies allows (in most cases) differentiation of congenital and acquired TTP from other thrombotic microangiopathies (e.g. HUS, atypical HUS, HELLP, PET etc).

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Testing Principle

The assay employs fluorescence resonance energy transfer (FRET) technology to allow measurement of ADAMTS-13 activity in citrated plasma. A recombinant peptide containing the cleavage site for ADAMTS-13 as well as an auto-quenching fluorochrome is added to patient plasma at 37°C. Cleavage of the substrate by ADAMTS-13 uncouples the fluorochromes resulting in an increased fluorescence which is relative to ADAMTS-13 activity.

Sample Requirements

Sample Type                Frozen citrated plasma (double centrifuged)

PRE-PLASMA EXCHANGE SAMPLES ARE PREFERRED

Volume required           2 x 0.5mL aliquots (preferred)

                                    1 x 100μL (minimum)

Assay Frequency          Monthly or performed urgently as required.

Cost                             $160.00 Routine sample batched once a month.

                                    $320.00 Urgent samples (830-1700 Mon-Fri).

                                    $450.00 Urgent samples (after hours and weekends)

For further information please contact:

Kent Chapman

Senior Technical Officer

Coagulation Department

Hunter Area Pathology Service (HAPS)

John Hunter Hospital

Ph:   02 49214419

Fax: 02 49214992

E: kent.chapman@hnehealth.nsw.gov.au

For Clinical Case Interpretation:

Dr Michael Seldon

Director of Haematology

Calvery Mater Hospital

Ph:  02 49211216

E: Michael.Seldon@mater.health.nsw.gov.au

Referral address for specimens:

Haematology Department

Hunter Area Pathology Service (HAPS)

Level 3, John Hunter Hospital

Lookout Rd

New Lambton Heights

Newcastle, N.S.W. 2305