Lupus Anticoagulant

About This Test

Department: Haematology

Requirement:

4 Citrate (Blue) tubes filled to the line.

Tubes must be filled to the line for accurate results.

 

Turnaround Time:

Up to 2 weeks (Samples are batched by the laboratory)

Patients with lupus anticoagulant (LA) are at an increased risk of arterial and venous thrombosis, in addition to obstetric morbidity.  Detection of LA may influence choice of anticoagulation and intensity of anticoagulation.  Testing for LA whilst on anticoagulation may result in false positive or false negative results, as the anticoagulation interferes with the laboratory testing.

 

Indications for LA testing may include:

  • Venous thromboembolism (VTE)
  • Arterial thromboembolism
  • Recurrent miscarriage/intra uterine death
  • Acute multiple thrombotic events and evidence of organ failure suggestive of catastrophic antiphospholipid syndrome (CAPS)
  • Unexplained isolated prolonged APTT following clinical haematology review (as if high-risk aPL profile may benefit from aspirin monotherapy)
  • Connective tissue disorders following specialist rheumatology review

 

Contra indications to LA testing:

  • Patients receiving anticoagulation with warfarin
  • Patients receiving anticoagulation with DOAC
  • During acute thrombotic event (because this can be confounded by acute changes and the effects of anticoagulants )
  • As APS is an acquired thrombophilia, screening for antiphospholipid antibodies is not recommended in family members of patients with thrombosis

Other Comments:

LA result reporting:

  • Reported as ‘Not detected / Detected / Indeterminate ‘
  • If LA positive, confirm result by repeating LA testing ≥ 12 weeks
  • If indeterminate, suggest repeat test after 1 week

 

Comments:

  • Also screen for cardiolipin antibodies and B2 glycoprotein antibodies (single gold bottle) – ‘APLS solid phase assays’
  • For patient receiving anticoagulation, discuss with clinical haematology.  Options include;
    • Transition to LWMH for >= 48 hours  and undertake trough LA (just prior to next dose of LWMH) alongside trough anti-factor Xa level
    • Omit DOAC for >=48 hours prior to LA testing (longer if renal impairment) with DOAC levels taken alongside