Test ID: QCMV
Cytomegalovirus, Molecular Detection, Quantitative PCR, Plasma
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Early detection of cytomegalovirus (CMV) viremia
Monitoring CMV disease and response to viral therapy
Method Name A short description of the method used to perform the test
Real-Time Polymerase Chain Reaction (PCR)/DNA Probe Hybridization
(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
Aliases Lists additional common names for a test, as an aid in searching
CMV by PCR
CMV Quant
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.
Container/Tube: Lavender top (EDTA)
Specimen Volume: 1 mL
Collection Instructions: Spin down and separate plasma within 24 hours of draw.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
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.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma EDTA | Refrigerated (preferred) | 7 days |
| Frozen | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cytomegalovirus (CMV) is 1 of the most important infectious agents of transplant recipients, causing significant morbidity and mortality. Direct effects of infection include fever, leukopenia, hepatitis, colitis, and 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).(1) The risk of CMV disease in solid organ allograft recipients is highest in patients who have a negative CMV serostatus prior to transplantation, and receive an allograft from a CMV seropositive individual. Other factors, such as the type of immunosuppressive protocol, age of the recipient, and comorbidities, may also be associated with an increased risk of CMV disease.
Available diagnostic techniques for CMV include serology (which for transplant recipients is used to determine the pretransplant serologic status of the donor and recipient), viral culture (conventional tube culture and shell vial cell culture), antigen detection, and nucleic acid detection by PCR. Of these, PCR assays demonstrate the most sensitive and specific detection of CMV, while allowing for quantitative monitoring of CMV DNA levels in peripheral blood over time.
In general, higher viral loads are associated with tissue-invasive disease, while lower levels are associated with asymptomatic infection. However, there is a wide degree of overlap in viral load and CMV disease. For this reason, trends in viral load over time may be more important in predicting CMV disease than a single absolute value. Recommendations for serial monitoring of transplant recipients with quantitative CMV PCR have been published.(6,7) In general, changes of >0.5 log(10) may represent a biologically significant changes in virus replication.
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.
None detected
Interpretation Provides information to assist in interpretation of the test results
A positive test result indicates the presence of cytomegalovirus (CMV) DNA; a quantitative value (copies/mL) is reported.
A result of "none detected" does not rule out the presence of CMV DNA (see Cautions).
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test should not be used as the only criterion to form a clinical conclusion; instead, results should be correlated with other test results, patient symptoms, and clinical presentation. The trend of viral loads over time may be more useful than a single absolute value for predicting the presence of cytomegalovirus (CMV) disease.
A result of "none detected" does not necessarily indicate the absence of CMV infection. False-negative results may be due to suppression of virus replication to levels below the detection threshold.
Some patients with tissue invasive disease may not have detectable viral load levels in peripheral blood. In these cases, qualitative detection of CMV DNA from tissue biopsy may provide useful adjunctive information.
This assay is only to be used for patients with a clinical history and symptoms consistent with CMV infection, and must be interpreted in the context of the clinical picture. This test should not be used to screen asymptomatic patients without risk factors for disease.
There is poor standardization between commercially available CMV PCR tests, and results from different institutions should not be directly compared. Quantitative results are best monitored using a single institution.
Inadequate specimen collection or storage may invalidate test results.
Supportive Data
The following validation data support the use of this test for clinical testing.
Accuracy/Diagnostic Sensitivity and Specificity:
The original Mayo PCR assay contained probes and primers specific for the Hind IIIX region of the cytomegalovirus (CMV) virus. Roche later developed analyte specific reagents (ASR) for the UL54 gene of CMV. In comparison studies of 328 plasma specimens submitted for CMV testing, the sensitivity and specificity of the Roche CMV ASR was found to be 94% and 100% respectively, as compared to the previous Mayo Hind IIIX Mayo CMV assay.
Analytical Sensitivity/Limit of Detection (LoD):
In studies performed with spiked patient specimens, the sensitivity of the Roche ASR assay was shown to be approximately 1,000 targets/mL (whole virus in specimen matrix).
Analytical Specificity:
No PCR signal was obtained from extracts of 44 bacterial and viral isolates including Epstein-Barr virus, herpes simplex virus, varicella-zoster virus, human herpesvirus-6, human herpesvirus-7, human herpesvirus-8, and parvovirus.
Precision:
Both intraassay and interassay precision met acceptance criteria of <0.25 log copies/mL.
Reference Range:
The reference range is "None Detected" for this assay.
Reportable Range:
The reportable range of this assay is 2,000 to 200,000,000 copies/mL. Acceptable linearity is present between these levels.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Razonable RR, Paya CV, Smith TF: Role of the laboratory in diagnosis and management of cytomegalovirus infection in hematopoietic stem cell and solid-organ transplant recipients. J Clin Microbiol 2002;40(3):746-752
2. Razonable RR, Brown RA, Wilson J, et al: The clinical use of various blood compartments for cytomegalovirus (CMV) DNA quantitation in transplant recipients with CMV disease. Transplantation 2002;73(6):968-973
3. Schaade L, Kockelkorn P, Ritter K, Kleines M: Detection of cytomegalovirus DNA in human specimens by LightCycler PCR. J Clin Microbiol 2000;38:4006-4009
4. Mendez JC, Espy MJ, Smith TF, et al: Evaluation of PCR primers for early diagnosis of cytomegalovirus infection following liver transplantation. J Clin Microbiol 1998;36(2):526-530
5. Razonable RR, Brown RA, Espy MJ, et al: Comparative quantitation of cytomegalovirus (CMV) DNA in solid organ transplant recipients with CMV infection by using two high-throughput automated systems. J Clin Microbiol 2001;39(12)4472-4476
6. Humar A, Syndman D, The AST Infectious Diseases Community of Practice: Cytomegalovirus in solid organ transplant recipients. Am J Transplant 2009;9(S4):S78-S86
7. 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
Method Description Describes how the test is performed and provides a method-specific reference
For this assay, viral DNA is extracted from 0.2 mL of plasma by the MagNA Pure automated instrument (Roche Applied Science). LightCycler PCR primers and probes have been designed to detect target cytomegalovirus (CMV) DNA in the UL54 gene of the virus. The LightCycler instrument amplifies and monitors target nucleic acid sequences by fluorescence during PCR cycling. This is an automated PCR system that can rapidly detect amplified product development. The detection of amplified products is based on the FRET principle. For FRET product detection, a hybridization probe with a donor fluorophore, fluorescein, on the 3' end is excited by an external light source, which emits light that is absorbed by a second hybridization probe with an acceptor fluorophore, LC-Red 640, at the 5' end. The acceptor fluorophore then emits light of a different wavelength that is measured with a signal that is proportional to the amount of specific PCR product. Quantitative results are obtained by incorporating known copy levels (5 standards) of CMV DNA (plasmid) into the assay, together with the specimen. LightCycler instrument software calculates the level of CMV DNA (copies/microliter) in the specimen from a standard curve of the quantitative levels of the reference plasmid CMV DNA. The process is completed in a closed tube system. (Unpublished Mayo method)
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; Varies
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.
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.
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.
87497
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 |
|---|---|---|
| 82986 | Cytomegalovirus PCR, Quant, P | 34720-3 |
| 21863 | Copies/mL | 29604-6 |
| 23521 | Lower 95% Confidence Interval | N/A |
| 23522 | Upper 95% Confidence Interval | N/A |
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