Overview
Anticardiolipin assays detect antibodies binding cardiolipin, typically in the presence of β2-glycoprotein I cofactor in standardized ELISAs.
Clinical Importance
Evaluate antiphospholipid syndrome (APS) laboratory criteria
Investigate thrombosis and pregnancy morbidity pathways per classification criteria
Specimen Requirements
- Specimen: serum (preferred for most serology/autoimmune immunoassays) or plasma when the method is validated
- Tube: gold/SST (serum separator) or red-top serum; follow method-specific plasma acceptability
- Handling: allow SST to clot fully; centrifuge and separate promptly; avoid repeated freeze–thaw
- Storage: refrigerate short-term; freeze aliquots for delayed testing per manufacturer stability
- Stability: analyte- and kit-specific; do not exceed validated time/temperature limits
Analytical Method
Solid-phase ELISA/CLIA quantifies aCL isotypes in GPL/MPL units. Persistently positive results ≥12 weeks apart are required for APS classification criteria.
Instruments Used
Automated analyzers
- Roche Cobas immunoassay systems
- Abbott Alinity / Architect immunoassay systems
- Siemens Healthineers Atellica / ADVIA Centaur immunoassay systems
- Beckman Coulter Access / DxI immunoassay systems
- bioMérieux VIDAS / BioFire immunoassays (selected analytes)
- Ortho Clinical Diagnostics Vitros immunoassay systems
- DiaSorin LIAISON immunoassay systems
- Phadia / Thermo Fisher ImmunoCAP allergy systems
- Manual ELISA, CLIA, and immunofluorescence platforms
Manual methods
- Manual ELISA, agglutination, and immunofluorescence methods in selected settings
Reference Values
Assay cutoffs, units, and reference intervals are method- and manufacturer-specific. Always interpret against the performing laboratory report (CLSI EP28-A3c for quantitative intervals where applicable). Serologic patterns require clinical correlation and current guideline algorithms (WHO/CDC/society guidance as adopted locally).
Method-specific cutoffs (often <20 GPL/MPL as negative/low). Medium/high titers matter for criteria; use the report’s thresholds.
Interpretation
Common Causes of Increased Results
- Positive aCL; interpret isotype, titer, persistence, and companion APS tests
Common Causes of Decreased Results
- Negative aCL; does not exclude APS if other criteria antibodies/LA are positive
Clinical Significance
- APS serology panel
Factors Affecting Results
Pre-analytical
- Hemolysis, lipemia, or icterus (assay-dependent interference)
- Wrong tube type or incomplete clotting of SST
- Repeated freeze–thaw of serum aliquots
- Testing too early or too late relative to infection/vaccination timing for serology
Analytical
- Inter-method variability of GPL/MPL units
- Transient infection-related positivities
Post-analytical
- Diagnosing APS on a single low-titer result
Advantages and Limitations
Advantages
- Standard APS solid-phase assay
Limitations
- Must be repeated for persistence
- Lupus anticoagulant is a clotting assay, not this immunoassay
Clinical Pearls
APS is a panel diagnosis timed 12 weeks apart; one anticardiolipin swallow does not make the syndrome.
References
Authoritative textbooks, guidelines, and reviews supporting this laboratory test reference. Verify reference intervals, critical limits, and method details against institutional protocols and current guideline editions.
Textbooks
- McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods (verify current edition). Chapters on clinical immunology and serology.
- Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics (verify current edition). Immunoassay and protein chapters.
CLSI and Professional Guidelines
- Centers for Disease Control and Prevention. Laboratory testing recommendations for infectious disease serology and related algorithms (verify current CDC guidance for the pathogen).
- Clinical and Laboratory Standards Institute. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory. CLSI document EP28-A3c (verify current edition).
- Clinical and Laboratory Standards Institute. Immunoassay and related method evaluation documents (e.g., EP05, EP06, EP07, EP17; verify current editions relevant to the assay).
- College of American Pathologists. Accreditation and proficiency testing expectations for immunology/serology (verify current CAP checklist requirements).
- International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). Recommendations relevant to protein and immunoassay measurands (verify current IFCC documents).
WHO Publications
- World Health Organization. Laboratory and diagnostic guidance for serologic and immunologic testing (verify current WHO publication for the analyte/assay).
Frequently Asked Questions
Common questions about using this Anticardiolipin Antibodies laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Anticardiolipin Antibodies laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Anticardiolipin Antibodies. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Anticardiolipin Antibodies specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Anticardiolipin Antibodies. Confirm collection details against your laboratory protocol.
Where are Anticardiolipin Antibodies reference values listed?
See the Reference Values section on this Laboratory Library page. Reference ranges can vary by method and population, so verify intervals with your laboratory.
How do I interpret Anticardiolipin Antibodies results?
Use the Interpretation section for laboratory interpretation framing, including increased and decreased result patterns when provided. Do not treat educational text as a patient-specific diagnosis.
What analytical method is used for Anticardiolipin Antibodies?
See the Analytical Method section for principle and method notes. Method details may differ by instrument and institutional SOP.
Are related laboratory tests linked from Anticardiolipin Antibodies?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Anticardiolipin Antibodies?
Use Continue learning links on this page for related Academy lessons, medical laboratory quizzes, or laboratory case studies when available for this Immunology & Serology topic.
What are the clinical pearls for Anticardiolipin Antibodies?
See the Clinical Pearls section for concise laboratory practice notes associated with Anticardiolipin Antibodies. Apply pearls alongside institutional protocols.
Reading progress
Awards XP once after you have meaningfully reviewed this article.