Overview
ANA detects autoantibodies binding nuclear (and some cytoplasmic) antigens, most often by indirect immunofluorescence on HEp-2 substrate.
Clinical Importance
Screen for systemic autoimmune rheumatic diseases (e.g., SLE, Sjogren, systemic sclerosis) when clinically indicated
Guide reflex specific autoantibody testing
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
Patient serum is incubated on HEp-2 slides; bound IgG is detected with fluorescent anti-human IgG. Titer and ICAP pattern are reported. ELISA/multiplex ANA screens exist but may differ in sensitivity/specificity from IFA.
Instruments Used
Automated analyzers
- Automated IFA slide processors and digital ANA pattern readers (selected laboratories)
- Multiplex bead immunoassays for ANA/ENA (method-dependent)
- Roche Cobas / Abbott Alinity / Siemens Atellica / DiaSorin LIAISON immunoassay systems for quantitative autoantibodies
Manual methods
- Manual indirect immunofluorescence (HEp-2) with fluorescence microscopy
- Manual ELISA for specific autoantibodies
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).
Screening dilution and positive cutoff are laboratory-defined (commonly 1:80 or 1:160 starting dilutions; verify local practice). Low-titer ANA can occur in healthy individuals.
Interpretation
Common Causes of Increased Results
- Positive ANA; report titer/pattern; clinical correlation mandatory; reflex dsDNA/ENA as indicated
Common Causes of Decreased Results
- Negative ANA; lowers likelihood of many ANA-associated diseases but does not exclude all autoimmune conditions
Clinical Significance
- Connective-tissue disease serology entry test
- Monitoring is generally not by repeating ANA once diagnosis is established
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
- Substrate lot, microscope setup, and reader variability on IFA
- ELISA screen false negatives/positives vs IFA
Post-analytical
- Ordering ANA without clinical pretest probability
- Repeating ANA for disease activity instead of specific markers/complements
Advantages and Limitations
Advantages
- Sensitive screen for many systemic autoimmune diseases
Limitations
- Low specificity at low titers
- Pattern alone is not a diagnosis
Clinical Pearls
A 1:80 speckled ANA in a healthy screen is usually not a rheumatology emergency; pretest probability still rules.
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 Antinuclear Antibody (ANA) laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Antinuclear Antibody (ANA) laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Antinuclear Antibody (ANA). Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Antinuclear Antibody (ANA) specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Antinuclear Antibody (ANA). Confirm collection details against your laboratory protocol.
Where are Antinuclear Antibody (ANA) 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 Antinuclear Antibody (ANA) 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 Antinuclear Antibody (ANA)?
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 Antinuclear Antibody (ANA)?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Antinuclear Antibody (ANA)?
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 Antinuclear Antibody (ANA)?
See the Clinical Pearls section for concise laboratory practice notes associated with Antinuclear Antibody (ANA). Apply pearls alongside institutional protocols.
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