Lupus anticoagulant

Alternative names, keywords

Samples required

2x trisodium citrate blood (blue cap, 3.5 mL tube) taken with minimal stasis, filled to the line, and

Clotted blood (gold cap, 5 mL tube).

Smaller tubes are available for paediatric samples.

Samples must be analysed or processed in the laboratory within 2 hours of venepuncture. Ideally patients should attend phlebotomy at the hospital to facilitate this.

Test indications

May be requested as part of thrombophilia screen, or as a separate test as in neurological or autoimmune investigations or recurrent miscarriage.

For patients on Warfarin or an anti-Xa Direct Oral Anticoagulant (DOAC) see Taipan Snake Venom Time (TSVT) and Ecarin Time (ET).

Test information

May be affected by presence of heparin in levels greater than 1U/mL.

Reference range

Reported by means of interpretive comment based upon one or more screening tests and the degree of phospholipid correction of that test, as per current BCSH guidelines (e.g. ‘Lupus anticoagulant not demonstrated’.)

A greater than 10% correction of the screening test with its confirmatory assay is considered indicative of LA.

A less than 7% correction of the screening test is considered not indicative of LA, i.e. negative.

Between 7% and 10% is equivocal and a repeat will be requested.

Turnaround time

1 month

Enquiries

Haematology (Coagulation)