Lupus anticoagulant (LA) is a heterogeneous autoimmune phospholipid antibody; typically IgG and/or IgM. The antibodies interfere with (prolong) phospholipid-dependent tests in-vitro in Coagulation including the Activated Partial Thromboplastin Time (APTT). Almost all Lupus anticoagulants are antiphospholipid antibodies (APAs), but not all APAs are Lupus Anticoagulants.
LA is associated with a thrombotic tendency, rather than bleeding and is also strongly associated with autoimmune disorders such as Systemic lupus erythematosus (SLE).
Ratio ≥1.2 indicates a positive result
Result interpretation is provided by the scientific and clinical team.
The volume of blood in coagulation samples must lie within the volume range as indicated by the size of the black fill arrow present on tubes. Volumes above or below the arrow will result in sample rejection to ensure validity of results.
Urgent: 4 hours
Routine: 3 weeks
- 2 blue top (sodium citrate) samples.
- All coagulation tubes must be adequately filled (see above).
- All coagulation tubes must be mixed several times by gentle inversion immediately after venepuncture. Mixing the sample with the anticoagulant stops the sample clotting within the tube.
- It is not possible to provide results on haemolysed, or lipaemic samples. These will be rejected with the appropriate comment.
- Sample tubes that have expired cannot be accepted.
Samples of patients who require Lupus anticoagulant testing, who are on warfarin may be referred for a Lupus Mix. These will be referred to the Sheffield Coagulation Reference Laboratory