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Immunology & Serology

CMV IgG

CMV IgG is a Immunology & Serology laboratory test reference in the LabPedia Medical Laboratory Library. Cytomegalovirus IgG; documents past exposure/immunity; paired sera or avidity assess recent infection timing.

Also known asCytomegalovirus IgG

Overview

CMV IgG indicates prior CMV infection; seroconversion or rising titers suggest recent infection.

Clinical Importance

Determine CMV serostatus (transplant, pregnancy, exposure counseling)

Support timing assessment with avidity when IgM is reactive

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

Immunoassays quantify or detect CMV IgG; avidity assays measure IgG binding strength after urea treatment.

Instruments Used

Automated analyzers

  • Roche Cobas immunoassay systems
  • Abbott Alinity / Architect immunoassay systems
  • Siemens Healthineers Atellica / ADVIA Centaur systems
  • DiaSorin LIAISON systems
  • bioMérieux VIDAS systems
  • Ortho Vitros immunoassay systems

Manual methods

  • Manual ELISA and rapid immunochromatographic serology tests

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).

Nonreactive = seronegative; reactive = past infection. Index values are method-specific.

Interpretation

Common Causes of Increased Results

  • CMV IgG reactive; latent/past infection serostatus

Common Causes of Decreased Results

  • CMV IgG nonreactive; susceptible to primary infection

Clinical Significance

  • Serostatus determination
  • TORCH and transplant serology

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

  • Calibration/QC failure; reagent lot shifts
  • Hook effect / antigen excess on selected immunoassays
  • Heterophile antibodies, rheumatoid factor, or biotin interference (assay-dependent)

Post-analytical

  • Applying another laboratory’s cutoff to a different method
  • Interpreting a single serology result without clinical timing and confirmatory algorithms

Advantages and Limitations

Advantages

  • Reliable serostatus marker

Limitations

  • IgG alone does not prove acute disease

Clinical Pearls

CMV IgG positive means the virus has been met . PCR decides whether it is active now.

Related Laboratory Tests

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 CMV IgG laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.

What is the CMV IgG laboratory test reference used for?

This Medical Laboratory Library page summarizes the clinical importance of CMV IgG. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.

Where can I find CMV IgG specimen requirements?

See the Specimen Requirements section on this page for specimen information related to CMV IgG. Confirm collection details against your laboratory protocol.

Where are CMV IgG 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 CMV IgG 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 CMV IgG?

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 CMV IgG?

Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.

How can I continue learning after reading CMV IgG?

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 CMV IgG?

See the Clinical Pearls section for concise laboratory practice notes associated with CMV IgG. Apply pearls alongside institutional protocols.

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