Cytomegalovirus IgG Avidity
Test Mnemonic
CMVAVI
CPT Codes
- 86644 - QTY (2)
Aliases
- Cytomegalovirus Antibody, IgG Avidity
Performing Laboratory
ARUP
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.5 mL | Serum | SST (Gold) | Refrigerated | Separate serum from cells ASAP or within 2 hours of collection and transfer into standard aliquot tube. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.15 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | After separation from cells: 48 hours |
| Refrigerated | After separation from cells: 2 weeks |
| Frozen | After separation from cells: 1 year |
Days Performed
Tue
Turnaround Time
2 - 9 days
Methodology
| Name | Description |
|---|---|
| Semi Quantitative Enzyme Linked Immunosorbent Assay |
Reference Range
| Cytomegalovirus IgG Avidity | |||||
|---|---|---|---|---|---|
| Sex | Age From | Age To | Type | Range | Range Unit |
| Low Avidity: 0.50 Index or less | Intermediate Avidity: 0.51 - 0.59 Index | High Avidity: 0.60 Index or greater |
Special Info
This test is New York DOH approved.
Clinical Info
Identifying CMV infections in pregnant women during the first trimester is of significant importance for clinical care. Acute infection is typically characterized by increased CMV-specific IgM and IgG antibodies. However, CMV IgM antibodies may persist for several months or even years after initial infection, which limits their utility in the accurate diagnosis of recent CMV infection. CMV IgM antibodies can also be detected during viral reactivation, thus complicating the diagnosis of a recent primary infection. Therefore, measuring IgG antibody avidity to CMV antigens can aid in discriminating recent from prior CMV infections. Index values of 0.5 or less generally indicate recent infection (within the previous 3 to 4 months). However low avidity values cannot exclude the possibility of persistent IgG antibodies with low avidity. Index values of 0.6 or greater indicate an infection occurring more than 3 months prior to testing. Because IgG avidity testing for CMV after the first trimester is not easily interpreted, detection of high avidity CMV IgG antibodies during the first trimester (12 to 16 weeks gestation) helps exclude a diagnosis of an acute CMV infection post-conception.