58170:CYTOMEGALOVIRUS (CMV) ANTIBODY, IgM

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58170:CYTOMEGALOVIRUS (CMV) ANTIBODY, IgM
Alias Names: CMV ANTIBODY, IgM
Methodology: Enzyme-Linked Immunosorbent Assay (ELISA)
Edit Date: 6/11/2010
Performed: Tuesday
Released: Same day as tested
CPT Code: 86645
Specimen Collection Details
Collection: One 7.5 mL serum separator tube (SST). Also acceptable: One 5 mL red top tube.
Handling: Allow to clot, centrifuge and separate serum from cells immediately. Refrigerate. Freeze at -20° C if specimen cannot be assayed within 48 hours. Allow no more than one freeze/thaw cycle. If multiple tests are ordered, send separate specimen for this test.
Standard Volume: 0.5 mL serum.
Minimum Volume: 200 µL serum.
Transport: Refrigerated if received in laboratory within 48 hours of collection, or frozen on dry ice.
Rejection Criteria: Plasma; heat inactivated or icteric specimen; gross lipemia; gross hemolysis; bacterial contamination; specimen that has been frozen and thawed more than once; refrigerated specimen received in laboratory more than 48 hours after collection.

Cytomegalovirus (CMV) IgM Antibody Result Interpretation, ELISA Method:

<0.9 IV (IV = Index Value)

<0.9 IV Negative: No significant level of detectable CMV IgM antibody.
0.9-1.0 IV Equivocal: Repeat testing in 10-14 days may be helpful.
≥1.1 IV Positive: IgM antibody to CMV detected, which may indicate a current or recent infection.

Appearance of IgM antibody response normally occurs 7-14 days after onset of disease. Testing immediately post-exposure is of no value without a later convalescent specimen. While the presence of IgM antibodies suggest current or recent infection, low levels of IgM antibodies may occasionally persist for more than 12 months post-infection. Such a residual IgM response may be distinguished from early IgM response to infection by testing sera from patients 2-3 weeks later for changing levels of specific IgM antibodies.

IgM responses may vary in different individuals. It has been reported that 10-30% of infants may fail to develop IgM antibody responses despite congenital CMV infection. Furthermore, up to 27% of adults with primary CMV infection may not demonstrate an IgM response. In immunocompromised patients, CMV serology may not be reliable and may be misleading in the diagnosis of acute or reactivation CMV disease.