Cytomegalovirus DNA Detection and Quantification, Plasma
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Detection and quantification of cytomegalovirus (CMV) viremia
Monitoring CMV disease progression and response to antiviral therapy
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Real-Time Polymerase Chain Reaction with TaqMan Probe Hybridization (RT-PCR)
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
CMV DNA Detect/Quant, P
CMV (Cytomegalovirus) Detection by Polymerase Chain Reaction (PCR), Plasma
CMV by PCR
CMV Viral Load
CMV by PCR
CMV Viral Load
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube: Lavender top (EDTA)
Submission Container/Tube: Plastic vial
Specimen Volume: 1.2 mL
1. Spin down and remove plasma from cells within 6 hours of draw.
2. Freeze plasma specimen immediately, and ship specimen frozen on dry ice.
3. If shipment will be delayed for >24 hours, freeze plasma specimen at -70 degrees C (up to 21 days) until shipment on dry ice.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild OK; Gross OK
Mild OK; Gross OK
Green-top (heparin) tube
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Plasma EDTA||Frozen (preferred)||21 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cytomegalovirus (CMV) is a common and major cause of opportunistic infection in organ transplant recipients, causing significant morbidity and mortality. CMV infection and disease typically occur during the first year after organ transplantation after cessation of antiviral prophylaxis. Such infection usually manifests as fever, leukopenia, hepatitis, colitis, or retinitis. Other manifestations of CMV infection in this population may be more subtle and include allograft injury and loss, increased susceptibility to infections with other organisms, and decreased patient survival (ie, indirect effects). The risk of CMV disease is highest among organ recipients who are CMV seronegative prior to transplantation and receive allografts from CMV-seropositive donors (ie, CMV D+/R- mismatch). The infection is transmitted via latent CMV present in the transplanted organ donor and the virus subsequently reactivates, causing a primary CMV infection in the recipient. CMV disease may also occur from reactivation of the virus already present within the recipients. Factors, such as the type of organ transplanted, intensity of the antirejection immunosuppressive therapy, advanced age, and presence of comorbidities in the recipient, are also associated with increased risk for CMV disease after allograft transplantation. Lung, heart, small intestine, pancreas, and kidney-pancreas transplant recipients are at greater risk for CMV infection than kidney and liver transplant recipients.
Among the various clinical laboratory diagnostic tests currently available to detect CMV infection, nucleic acid amplification tests (eg, PCR) are the most sensitive and specific detection methods. In addition, quantification of CMV DNA level in peripheral blood (ie, CMV viral load) is used routinely to determine when to initiate preemptive antiviral therapy, diagnose active CMV disease, and monitor response to antiviral therapy. A number of factors can affect CMV viral load results, including the specimen type (whole blood versus plasma), biologic properties of CMV, performance characteristics of the quantitative assay (eg, limit of detection, limits of quantification, linearity, and reproducibility), degree of immunosuppression, and intensity of antiviral therapy.
In general, higher CMV viral loads are associated with tissue-invasive disease, while lower levels are associated with asymptomatic infection. However, the viral load in the peripheral blood compartment may be low or not detectable in some cases of tissue invasive disease. Since wide degree of overlap exists in CMV viral load and disease, rise in viral load over time is more important in predicting CMV disease than a single viral load result at a given time point. Therefore, serial monitoring (eg, weekly intervals) of organ transplant recipients with quantitative CMV PCR is recommended in such patients at risk for CMV disease. Since changes in viral load may be delayed by several days in response to antiviral therapy and immunosuppression, viral load should not be monitored more frequently than a weekly basis. Typically, CMV viral load changes of >0.5 log IU/mL are considered biologically significant changes in viral replication. Patients with suppression of CMV replication (ie, viral load of <137 or <2.1 log IU/mL at days 7, 14, and 21 of treatment) had shorter times to resolution of clinical disease than those without viral suppression. No degree of relative viral load reduction from pretreatment level was associated with faster resolution of CMV disease.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
The quantification range of this assay is 137 to 9,100,000 IU/mL (2.14 log to 6.96 log IU/mL), with a > or =95% limit of detection at 91 IU/mL (1.96 log IU/mL).
A result of "Undetected" indicates the absence of cytomegalovirus (CMV) DNA in the plasma (see Cautions below).
A result of "Detected, but <137 IU/mL (<2.14 log IU/mL)" indicates that CMV DNA is detected in the plasma, but the assay cannot accurately quantify the CMV DNA present below this level.
A quantitative value (reported in IU/mL and log IU/mL) indicates the level of CMV DNA (ie, viral load) present in the plasma.
A result of "Detected, but >9,100,000 IU/mL (>6.96 log IU/mL)" indicates that CMV DNA level present in plasma is above 9,100,000 IU/mL (6.96 log IU/mL), and the assay cannot accurately quantify CMV DNA present above this level
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Cytomegalovirus (CMV) DNA level in plasma should not be used as the only criterion used in the diagnosis and therapeutic decision for CMV disease. Viral load should be correlated with other laboratory test results and clinical presentation. The trend of viral load over time is more useful than a single absolute value for predicting the presence of CMV disease.
A result of "Undetected" does not necessarily indicate the absence of CMV infection, since low-level viral replication may be below the limit of detection of the assay. False-negative or falsely low viral load results can be caused by improper specimen collection or storage prior to testing.
Some patients with tissue-invasive CMV disease may not have detectable viral load in the peripheral blood. In such cases, CMV-specific immunohistochemical stains and qualitative detection of CMV DNA from tissue biopsy would provide useful and definitive evidence of CMV disease.
This assay should be used only to test plasma from at-risk patients with a clinical history and symptoms and signs suggestive with CMV infection; viral load results must be interpreted in the context of the clinical picture. This test is not indicated for screening asymptomatic patients without risk factors for CMV disease.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Kotton CN, Kumar D, Caliendo A, et al: International consensus guidelines on the management of cytomegalovirus in solid organ transplantation. Transplantation 2010;89(7):779-795
2. Kraft CS, Armstrong WS, Caliendo AM: Interpreting quantitative cytomegalovirus DNA testing: understanding the laboratory perspective. Clin Infect Dis 2012;54(12):1793-1797
3. Razonable RR, Asberg A, Rollag H, et al: Virologic suppression measured by a cytomegalovirus (CMV) DNA test calibrated to the World Health Organization international standard is predictive of CMV disease resolution in transplant recipients Clin Infect Dis 2013 Jun;56(11):1546-1553
Method Description Describes how the test is performed and provides a method-specific reference
The COBAS AmpliPrep/COBAS TaqMan CMV Test is an FDA-approved in vitro nucleic acid amplification test for the quantification of cytomegalovirus (CMV) DNA in human plasma using the COBAS AmpliPrep instrument for automated viral nucleic acid extraction (generic silica-based capture technique) and the COBAS TaqMan analyzer for automated amplification and detection of the viral nucleic acid target. This assay targets the highly-conserved, nondrug target region of the CMV DNA polymerase (UL54) gene. Generic silica-based specimen preparation is used to capture the CMV DNA and an internal control CMV quantitation standard (QS) DNA, and defined oligonucleotides are used as primers in amplification of the CMV DNA and CMV QS DNA. A target specific and a QS-specific dual-labeled oligonucleotide probe permit independent identification of the CMV amplicon and of the CMV QS amplicon. The COBAS AmpliPrep/COBAS TaqMan CMV Test uses 2 amplification primers for PCR. A fluorescent, signal-generating probe modified with a 5' fluorochrome (FAM) and a 3' quencher hybridizes to 1 of the 2 strands and is cleaved by Z05 DNA polymerase during extension of the primers. Cleavage of the probe physically separates the quencher from the reporter, enabling light emitted by the latter to be detected by a photomultiplier tube. Because amplification and detection are performed simultaneously, amplification products are measured during the exponential phase of DNA amplification regardless of the initial target concentration.
The COBAS AmpliPrep/COBAS TaqMan CMV Test quantitates CMV viral DNA by analyzing the difference between the CMV target and QS Ct values. The CMV QS is a noninfectious DNA construct containing fragments of CMV sequences with primer binding regions identical to those of the CMV target sequence. The CMV QS contains CMV primer binding regions and generates an amplification product of the same length and base composition as the CMV target DNA. The detection probe binding region of the CMV QS has been modified to differentiate CMV QS amplicon from CMV target amplicon. During the extension phase of the PCR in the COBAS TaqMan Analyzer, the specimens are illuminated and excited by filtered light and filtered emission fluorescence data are collected for each specimen. The readings from each specimen are then corrected for instrumental fluctuations. These fluorescence readings are sent by the instrument to the AMPLILINK software and stored in a database. Pre-Checks are used to determine if the CMV DNA target and CMV QS DNA data represent sets that are valid, and flags are generated when the data lie outside the preset limits. After all Pre-Checks are completed and passed, the fluorescence readings are processed to generate Ct values for the CMV DNA target and the CMV QS DNA. The lot-specific calibration constants provided with the COBAS AmpliPrep/COBAS TaqMan CMV Test are used to calculate the titer value for the specimens and controls based on both the CMV DNA target and CMV QS DNA Ct values. Titer results are reported in International Units/mL (IU/mL).(Package insert: COBAS AmpliPrep/COBAS TaqMan CMV Test; Roche Molecular Systems, Inc., Branchburg, NJ, 9/2010)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 7 a.m.-4 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Monday through Friday; 1 day Saturday; 3 days
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|61861||CMV DNA Detect/Quant, P||72494-8|