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PTD - 195

Test Directory -  Cardiolipin antibodies


Anticardiolipin antibodies, ACA, ACLIP, as part of lupus anticoagulant.

Clinical Indications

Suspicion of antiphospholipid syndrome (APS, Hughes syndrome). Diagnosis of APS requires a clinical history of vascular thrombosis or pregnancy morbidity, together with positive lupus anticoagulant or elevated cardiolipin antibodies on two or more occasions 12 weeks apart.

Test Includes

IgG and IgM antibodies to cardiolipin. The anticardiolipin assay would normally be positive if B2 glycoprotein 1 antibodies are present, however may be tested if there is compelling clinical evidence. Positive and weak positive results will be reflex tested for IgG and IgM B2 glycoprotein-1 antibodies.

Request Form

Combined Pathology Blood form (Yellow/Black)


Referred test: Analysed by Immunology, Southend Hospital.

Specific Criteria

No repeat within 3 months and, once tested, B2 glycoproteins are not routinely repeated.

Patient Preparation

None required

Turnaround Time

2 weeks (may be longer if B2 glycoproteins are required as these are sent to Sheffield Protein Reference Unit)




2 ml


Yellow top (SST) tube or

Paediatric brown top

Causes for Rejection

Unlabelled sample. Repeat analysis within previous 3 months


Cardiolipin IgG and IgM antibodies:
Negative            0 9.9 u/mL
Equivocal          10 40 u/mL
Positive            >40       u/mL

The likelihood of APS is increased if both ACA and Beta-2 GP1 are positive, but APS is possible with only ACA positive. Positive ACA may also be seen in other autoimmune conditions and infection, which may be cryptic, should be excluded. Positive results should be repeated after 12 weeks.

Lab. Handling

Processing: Immunology at the Hub laboratory

Version 1.1 / Feb 2017                                                                                                          Approved by: Consultant Biochemist