Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1345 page)

   
Normal range:
Negative.

   Serology reporting is done as qualitative (negative, equivocal or positive) based on the cutoff values established by manufacturer-specific clinical trials. A negative result, however, does not always rule out acute hCMV infection. The IgM response may not be detectable in the very early stage of the infection or if the patient is immunocompromised. If clinical exposure to hCMV is suspected despite a negative finding, a second sample should be collected and tested no <1 or 2 weeks.

   Limitations

   Screening of the general population should not be performed. The positive predictive value depends on the likelihood of the virus being present. Testing should only be performed on patients with clinical symptoms or when exposure is suspected. Diseases such as Epstein-Barr viral syndrome, toxoplasmosis, and hepatitis may cause symptoms similar to CMV infection and must be excluded before confirmation of diagnosis.

EPSTEIN-BARR VIRUS (EBV) MOLECULAR TESTING
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   Definition

   Epstein-Barr virus (EBV) quantitative PCR detects the presence of EBV DNA in clinical specimens, most commonly plasma or serum. Normal adults usually do not have detectable EBV DNA in their plasma/serum, although normal adults previously infected with EBV will have low levels of EBV DNA in their lymphocytes.

   Use

   Monitoring the level of viral reactivation and/or disease activity, particularly in the posttransplant and chemotherapy patients.

   In diagnosis, prognosis, prediction, and prevention of diseases as mononucleosis, lymphoma, sarcoma, and carcinoma.

   EBV viral load in whole blood reflects clinical status in patients with infectious mononucleosis, allogeneic transplant, and nasopharyngeal carcinoma.

   The EBV DNA level in healthy carriers is low and restricted to the intracellular compartment of the blood. The high level is characteristic of EBV-related disease.

   Patients with active infection or EBV-related cancer tend to have high levels of EBV DNA in the plasma or serum.