Test ID: CMG
Cytomegalovirus (CMV) Antibodies, IgG, Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Determining whether a patient (especially organ donors, blood donors, and prospective transplant recipients) had cytomegalovirus (CMV) infection in the past
Excluding CMV current infection (cord blood)
Method Name A short description of the method used to perform the test
Enzyme-Linked Fluorescence Assay (ELFA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Cytomegalo Inclusion Disease (CMID)
Cytomegalovirus (Antibody Titer)
Torch IgG
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 0.5 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cytomegalovirus (CMV) is a significant cause of morbidity and mortality, especially in organ transplant recipients and individuals with acquired immunodeficiency syndrome (AIDS). (1,2) CMV is also responsible for congenital disease of the newborn. The most common infections with CMV in immunocompromised hosts result from reactivation of latent virus from a previous infection, transmission of the virus from a donor organ or blood product, or initial or primary contact with the virus in a seronegative patient. Infection in immunologically normal patients can cause mononucleosis similar to that produced by infection with Epstein-Barr virus (EBV).
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
<4 AU/mL (negative)
4-5 AU/mL (equivocal)
> or =6 AU/mL (positive)
A convalescent IgG antibody level of >6 AU/mL combined with a ratio of > or =2 in a paired sera (seroconversion) IgG titer indicates recent infection. The presence of only IgG antibodies generally indicates past infection with CMV.
Interpretation Provides information to assist in interpretation of the test results
Individuals with negative cytomegalovirus (CMV) IgG results are presumed to have not experienced infection with CMV and, therefore, are susceptible to primary infection.
Positive CMV IgG results indicate past or current CMV infection. Such individuals are potentially at risk of transmitting CMV infection through blood products; the likelihood of transmission by other modes is not known.
A ratio of > or =2 in paired sera (acute and convalescent) IgG values, along with a convalescent antibody level of >6, indicates a seroconversion has occurred and is indicative of a recent infection.
CMV infections are quite common. Approximately 60% to 85% of the population is believed to be infected by age 18.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Sera drawn very early in the acute stage of disease may have IgG levels <4 AU/mL.
The VIDAS cytomegalovirus (CMV) IgG assay demonstrates a linear dilution response to concentration. However, no international standard has been established.
The IgG titer of a single specimen should not be used to aid in the diagnosis of recent infection. Paired (acute and convalescent) specimens should be drawn and tested concurrently to look for seroconversion, which may be indicative of primary or recent infection, or of reactivation of a pre-existing latent process with active viral excretion.
Positive test results may not be valid in persons who have received blood transfusions or other blood products in the past several months.
Lack of a significant increase in IgG antibody level does not exclude the possibility of CMV infection.
Results must be used in conjunction with clinical symptoms and patient history.
This test should not be used as a general screen in the absence of clinical symptoms or known exposure.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Kusne S, Shapiro R, Fung J: Prevention and treatment of cytomegalovirus infection in organ transplant recipients. Transpl Infect Dis 1999;1(3):187-203
2. Rubin RH: Importance of CMV in the transplant population. Transpl Infect Dis 1999;1(1):3-7
Method Description Describes how the test is performed and provides a method-specific reference
VIDAS cytomegalovirus (CMV) IgG is an enzyme-linked fluorescent immunoassay (ELFA) performed by an automated VIDAS instrument. All assay steps are controlled by the instrument.
In the test, CMV IgG antibodies bind to CMV antigen coated on a solid-phase pipetter. Antihuman IgG antibody conjugated with alkaline phosphatase binds to specific antigen-antibody complexes. A fluorescent substrate, 4-methylumbelliferyl phosphate, is added. In the presence of bound enzyme, the substrate is converted to the fluorescent product, 4-methylumbelliferone. The intensity of fluorescence is measured by the optical scanner in the VIDAS instrument. (Package insert: VIDAS CMV IgG, bioMerieux, Inc., Durham, NC)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; Varies
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
86644
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| CMG | Cytomegalovirus Ab, IgG, S | 5124-3 |
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