Effective Dec. 22, 2025

Provincially standardized Lupus Anticoagulant testing, currently performed at the Health Sciences Centre Hemostasis Laboratory, utilizes two assays in the testing algorithm (Dilute Russell Viper Venom [DRVV] and Time and lupus-sensitive APTT [PTT-LA] with and without added phospholipids). The existing PTT-LA assay will transition to a Hexagonal Phase Phospholipid PTT-LA kit assay (Precision Biologic, HEXLA kit). This test utilizes the Werfen (previously known as Instrumentation Laboratory or IL) ACL TOP series coagulation analyzers.

Clinical Practice Change:

• PTT-LA results utilizing the HEXLA kit are reported as the Delta value (change in value) between the PTT-LA Start (Lupus sensitive APTT) and PTT-LA Correct (Lupus sensitive APTT with added hexagonal phospholipid).
  • ‘PTT-LA Delta’ value is reported in seconds(s).
  • The reference range is <10.9(s).
  • PTT-LA Delta is reported on the patient report when it exceeds the reference range.
  • PTT-LA Test Ratios are not performed and will no longer appear on patient reports.
• Lupus Anticoagulant interpretation will continue to be reported as ‘Demonstrated’ or ‘Not Demonstrated’ on all requests.

References | Resources:

Please refer to the Laboratory Information Manual (LIM) Lab Information Manual

System Improvements:

• Streamlined laboratory workflow for Lupus Anticoagulant testing and consumables.
• Improved turnaround time for result reporting.
• Improved utilization of laboratory resources.

Access a printable file.

Submitted by: Tamara Burnham, Collaborative Practice Lead