4-7 ml whole blood; for infants a volume of 2-4 ml is acceptable
4 ml whole blood; for infants a volume of 2 ml is acceptable
Transport blood in a timely fashion (preferably within 8 hours of collection) at room temperature to the Clinical Virology Laboratory.
Whole blood in an EDTA-anticoagulated tube is the preferred specimen source. Thoroughly mix the blood by gently inverting the collection tube 6-12 times before sending to the laboratory. Other acceptable specimens include body fluids, tissue submitted in viral transport medium, and CSF.
If qualitative CMV DNA real-time PCR is positive from blood, a quantitative assay will be performed to measure the amount of CMV DNA present.
87496 (qualitative CMV DNA PCR screening), 87497 (quantitative viral load determination, if necessary)
Amplification and detection of CMV DNA polymerase gene using TaqMan real-time PCR technology. This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.
If positive, results are reported as cytomegalovirus DNA detected.
Negative or no cytomegalovirus DNA detected
Clinical Utility: CMV infections are common and usually asymptomatic in otherwise healthy children and adults; however, the incidence and spectrum of disease in newborns and in immunocompromised hosts establish this virus as an important human pathogen. Real-time PCR is widely used for the direct detection and quantification of CMV from blood leukocytes in recipients of solid-organ and bone marrow transplants, cancer patients (particularly those with leukemia and lymphoma receiving chemotherapy), and individuals infected with HIV who are suspected of having systemic CMV infection. Quantitative measures of CMV DNA can provide a rapid diagnosis of established disease, identify patients at risk of developing disease, assess the progression of disease and the risk of relapse, direct the initiation of preemptive therapy, monitor the response to antiviral therapy, and predict treatment failure and the emergence of drug-resistant virus. In general, immunocompromised patients with active CMV disease are viremic and have elevated levels of CMV DNA in their blood; a rapid rise in CMV DNA copy number correlates with the progession to or presence of symptoms and drug failure during treatment. PCR has also been used to find CMV DNA in the blood of infants with congenital infection. Detection of CMV DNA from maternal blood leukocytes may provide useful information for prenatal diagnosis of congenital infection. While such prenatal testing is a sensitive indicator of maternal CMV infection, positive results do not predict which infants will be infected and have disease. Recently, it has been demonstrated that elevated levels of CMV DNA in blood during early infancy is associated with hearing loss in newborns with symptomatic and asymptomatic congenital CMV infection. PCR of blood also can be helpful in patients suspected of having CMV-associated bone marrow suppression, hemophagocytic syndrome, hemolytic anemia, and an atypical lymphocytosis.
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