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ADAMTS 13 Activity (ACUSTAR) LTHT Patients ONLY

citrate
ADAMTS13 cleaves Von Willebrands factor into smaller multimers. A deficiency of ADAMTS 13, or inhibition of ADAMTS13 activity leads to very large Von Willebrands multimers being released into the circulation. These activate platelets causing aggregation and the formation of micro-thrombi. The poor prognosis associated with TTP requires early, accurate diagnosis.

Department

Specialist Coagulation

Tube

05 (CP) – Citrate

Turn Around

Inpatient (acute) – 2 hours

Inpatient (routine) – 5 days

GP (acute/routine) – Not available to GPs – discuss with the on-call haematology consultant

Send to

Specialist Coagulation
Centre for Laboratory Medicine
St James University Hospital
Beckett Street
Leeds
LS9 7TF

Specialist Coagulation

Collection Conditions

2 x Citrate tube filled to line please.

Sample Storage

Citrated plasma. Must be processed or plasma frozen (within 6 hours of collection).

Availability

24/7

Ref. Range Notes

Male = 60.6 – 130.6

Female = 60.6 – 130.6

Paed = 60.6 – 130.6 (Please note that these are adult reference ranges and may not apply to patients <12 months old. Interpretation of results must always be done in light of the clinical setting.)

Frequency

As required

Additional Information

During normal working hours, all requests must be authorised by a haematology Consultant or SpR. The haematology Consultant or SpR must verbally inform the appropriate scientist in specialist coagulation that they have authorised the test. Failure to so will result in a delay to testing. Outside of normal working, all requests must go via the on call Haematology Consultant.
Important information on result interpretation If the ADAMTS13 activity is greater than 10 IU/dL TTP can be excluded as long as there are no confounding factors such as the patient having been given fresh frozen plasma.   An ADAMTS13 result <2 IU/dL is highly suggestive of TTP. Note that all results of 10 IU/dL or less will be confirmed by ADAMTS13 FRET assay at the Royal Hallamshire Hospital in Sheffield.   If the ADAMTS13 result is between 2 and 10 IU/dL TTP is possible and further information will subsequently become available from the FRET assay. In all cases the appropriate clinical management of the patient must be discussed with a haematology consultant +/- the TTP centre in Sheffield as on some occasions starting treatment before test results are available is warranted.
WinPath Code:
AD13