Cytomegalovirus IgG Avidity


Sunquest Code:CMVAV  
Epic Code:LAB6585Epic Name:Cytomegalovirus IgG Avidity
Synonyms:CMV IgG Avidity; Cytomegalovirus Antibody, IgG Avidity
Methodology:Enzyme-linked immunosorbent assay
Turnaround Time:Specimens are sent to reference laboratory Mon-Sat; results are reported within 1-8 days.
Compliance:

This test was developed and its performance characteristics determined by ARUP Laboratories. The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.



Collection Instructions

Specimen:Blood
Optimal Volume:1 mL
Minimum\Peds Volume:0.5 mL
Container:Red or gold (gel) (Red (no gel))


Processing and Shipping

Specimen Processing:Within 2 hours of collection, centrifuge and aliquot 0.5 mL, 0.15 mL minimum. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Stability:Stability: After separation from cells samples are stable for 48 hours at room temperature, 2 weeks refrigerated and 1 year frozen.
Test Performed at or Referral Lab Lab Sendouts  (ARUP)
Referral Lab number:2011813


Interpretive

Reference Range:

0.50 Index or less

Low avidity

0.51 – 0.59 Index

Intermediate avidity

0.60 Index or greater

High avidity

 

 

Use: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 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.


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