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Cytomegalovirus Serology

Alias: CMV

Discipline: Virology

Test information: CMV IgM is used in the diagnosis of primary cytomegalovirus infection, though it may also be reactive with CMV reactivation. Particularly significant in immunocompromised or pregnant patients. Positive test results may not be valid in persons who have received blood transfusions or other blood products within the past several months.

Following primary infection, CMV IgG persists lifelong. This test is used to determine CMV serological status, indicating whether patient has already been infected with CMV. Used to determine CMV IgG status of transplant donors and recipients. May also be used prior to administration of immunosuppressive therapy. This test should not be repeated within one week.

CMV IgG is also included in diagnostic profile for primary CMV infection, when CMV IgM has been detected.

CMV IgG Avidity testing is used as an aid in the differentiation between primary and non-primary infection.

Availability: Available locally Monday - Friday locally during routine hours: 08:45 - 17:15.

Turnaround Time: 4 Days

Specimen Type(s)
  • Clotted blood;
Other Acceptable Specimen Type(s)
Specimen Container - Adult
  • Gold Top SST BD;
Specimen Container - Paediatric
  • Plain Top Sarstedt;
  • Cytomegalovirus antibodies;
Part of a test profile?
Volume (min) of sample to be sent to laboratory
Patient Preparation, Sample Handling and Transport
  • Minimum-clotting time 30 minutes.
  • Specimens should be transported to the laboratory as soon as possible.
  • Outside of normal hours samples should be refrigerated (2 °C to 8 °C).
  • Do NOT send grossly haemolyzed specimens (>500 mg/dL haemoglobin).
  • Do NOT send specimens with obvious microbial contamination.
Maximum add on time
Units and Reference Ranges / Interpretation

CMV IgM Antibody: Non reactive / Reactive

CMV IgG Antibody: Non reactive / Reactive

CMV IgG Antibody Units: AU/mL

Specimens with concentration values <6.0 AU/mL are considered nonreactive for IgG antibodies to CMV.

Specimens with concentration values >6.0 AU/mL are considered reactive for IgG antibodies to CMV.

If primary infection needs to be excluded, CMV IgG reactive samples will be tested for CMV IgM and CMV IgG Avidity. A positive CMV IgM result in combination with a low avidity result is a strong indicator for a primary CMV infection within the last 4 months.
UKAS number
UKAS accredited test?

Performance has not been established using cadaver specimens. These tests may give false negative results on severely immunocompromised patients.

IgM rheumatoid factor in combination with CMV specific IgG can lead to false reactive IgM .

Heterophilic antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animal or to animal serum products can be prone to this interference.

Specimens from patients who have received preparations of mouse monoclonal antibodies for diagnosis or therapy may contain human anti-mouse antibodies (HAMA). Specimens containing (HAMA) may produce anomalous values when tested.

If you have any queries about a test or results interpretation please contact us.

Last updated: 11-07-2023