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 mLSerumSST (Gold) RefrigeratedSeparate 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
AmbientAfter separation from cells: 48 hours
RefrigeratedAfter separation from cells: 2 weeks
FrozenAfter 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.