Test Catalog

Test Id : PBKQN

BK Virus DNA Detection and Quantification, Plasma

Useful For
Suggests clinical disorders or settings where the test may be helpful

Detection and serial monitoring of BV virus-associated nephropathy in kidney transplant recipients using plasma specimens


Detection and serial monitoring of BV virus-associated hemorrhagic cystitis in organ transplant recipients


This assay detects and quantifies the level of BK virus (BKV) DNA present in the plasma of kidney transplant recipients who are at risk of developing BKV-associated nephropathy leading to decreasing kidney function and eventual kidney failure. The assay is calibrated to the First World Health Organization International Standard for BKV DNA.

Method Name
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (RT-PCR)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

BKV DNA Detect/Quant, P

Lists additional common names for a test, as an aid in searching

BK viral load

BK virus by PCR

BK virus DNA quant


BKV DNA quant

BKV viral load

Specimen Type
Describes the specimen type validated for testing

Plasma EDTA

Shipping Instructions

1. Ship specimen frozen on dry ice only.

2. If shipment will be delayed for more than 24 hours, freeze plasma at -20 to -80 degrees C (up to 84 days) until shipment on dry ice.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 1.5 mL

Collection Instructions:

1. Centrifuge blood collection tube per manufacturer's instructions (eg, centrifuge within 2 hours of collection for BD Vacutainer tubes).

2. Aliquot plasma into plastic vial.


Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis OK
Gross lipemia OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Plasma EDTA Frozen (preferred) 84 days
Refrigerated 6 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Detection and serial monitoring of BV virus-associated nephropathy in kidney transplant recipients using plasma specimens


Detection and serial monitoring of BV virus-associated hemorrhagic cystitis in organ transplant recipients

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

BK virus (BKV) is a circular, double-stranded DNA virus with an approximately 5 kilobase-size genome in the polyomavirus family, of which 13 members of the family are known, including the JC virus (JCV) and SV40. BKV shares about 75% of its DNA sequence with JCV. Nearly 80% of the adult population worldwide have antibodies to both viruses, indicating previous infection or exposure to these viruses.


Initial infection with BKV is usually acquired in childhood, mostly asymptomatic or manifesting as a mild flu-like illness. After primary infection, BKV establishes latency in the kidney and bladder of the infected individual. In the setting of immunosuppression, the virus reactivates and begins to replicate, triggering renal tubular cell lysis and viruria. As the reactivation progresses, the virus multiplies and crosses into the bloodstream, causing viremia and invading the kidney graft. In patients with kidney transplants, reactivation of BKV typically reaches peak incidence at 3 months posttransplantation with BK viral replication in the kidney graft, causing BKV-associated nephropathy (BKVAN), which manifests as kidney dysfunction that may result in eventual loss of the transplanted kidney. Reactivation of BKV in the bladder can lead to hemorrhagic cystitis. Currently, there are no US Food and Drug Administration-approved antiviral agents or treatments for BKVAN or BKV-associated hemorrhagic cystitis. The main treatment is to decrease the immunosuppression, with the risk of acute rejection of the kidney graft.


After BK reactivation, the virus is first detectable in the urine, with viremia developing several weeks later. Quantitative BKV DNA in the plasma is the most widely used and preferred test for the laboratory diagnosis of BKVAN and BKV-associated hemorrhagic cystitis, as BKV viremia has higher positive predictive value (50%-60%) than BKV viruria for the diagnosis of BKVAN. Serial monitoring of BKV DNA level in plasma is recommended to guide optimal immunosuppressant dosing regimen. In those with BKVAN, clearance of BK viremia is a sign of resolution of the nephropathy.

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.


Provides information to assist in interpretation of the test results

The quantification range of this assay is 22 to 100,000,000 IU/mL (1.34 log to 8.00 log IU/mL), with a limit of detection (95% detection rate) at 22 IU/mL.


An "Undetected" test result indicates the absence of BK virus (BKV) DNA in the plasma.


A test result of "<22 IU/mL (<1.34 log IU/mL)" indicates that BKV DNA is detected in the plasma, but the assay cannot accurately quantify the BKV DNA present below this level.


A quantitative value (reported in IU/mL and log IU/mL) indicates the level of BKV DNA (ie, viral load) present in the plasma.


A test result of ">100,000,000 IU/mL (>8.00 log IU/mL)" indicates that BKV DNA level present in plasma is above 100,000,000 IU/mL (8.00 log IU/mL), and the assay cannot accurately quantify BKV DNA present above this level.


An "Inconclusive" result indicates that the presence or absence of BKV DNA in the plasma specimen could not be determined with certainty after repeat testing in the laboratory, possibly due to polymerase chain reaction inhibition or presence of interfering substance. Submission of a new specimen for testing is recommended if clinically indicated.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

On average, quantitative BK virus (BKV) DNA results in plasma tested with this assay can be up to 1.4-fold (about 0.15 log IU/mL) higher than those generated from the previous laboratory-developed BKV DNA quantification assay performed at Mayo Clinic Laboratories, due to differences in the specimen extraction method and design in the amplification primers and probes for the viral target sequences.


A single "Undetected" test result does not necessarily rule out the presence BKV infection or reactivation. Serial measurement (eg, once weekly) of BKV DNA in plasma is recommended to determine the BKV replication status in a given transplant recipient.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Bechert CJ, Schnadig VJ, Payne DA, Dong J: Monitoring of BK viral load in renal allograft recipients by real time PCR assays. Am J Clin Pathol. 2010 Feb;133(2):242-250. doi: 10.1309/AJCP63VDFCKCRUUL

2. Hirsch HH, Randhawa P, AST Infectious Diseases Community of Practice: BK polyomavirus in solid organ transplantation. Am J Transplant. 2013 Mar;13 Suppl 4:179-188. doi: 10.1111/ajt.12110

3. Hirsch HH, Randhawa PS, AST Infectious Diseases Community of Practice: BK polyomavirus in solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice. Clin Transplant. 2019 Sep;33(9):e13528. doi: 10.1111/ctr.13528

4. Muhsin SA, Wojciechowski D: BK virus in transplant recipients: current perspectives. Transplant Research and Risk Management. 2019 Sep:11:47-58. doi: 10.2147/TRRM.S188021

Method Description
Describes how the test is performed and provides a method-specific reference

The cobas BK virus (BKV) assay is an FDA-approved, in vitro nucleic acid amplification test for the quantification of BKV DNA in human EDTA-plasma using either the cobas 6800 or 8800 system for fully automated viral nucleic acid extraction (generic silica-based capture technique) and automated amplification and detection of the viral RNA. This dual-target polymerase chain reaction (PCR) assay amplifies 2 highly-conserved target regions within the BKV genome (small t-antigen and VP2 regions) for real-time detection and quantification by 2 target-specific TaqMan probes. A non-BKV armored DNA quantitation standard (DNA-QS) is introduced into each specimen during sample preparation to serve as internal control for nucleic acid extraction and PCR amplification and detection processes. Fluorescent reporter dye-labeled TaqMan probes hybridized to the complementary BKV target sequences and DNA-QS sequence undergo hydrolysis during PCR amplification step to generate fluorescent signal detected in 3 different dye channels. Concentration of the BKV DNA in a patient's plasma sample is determined by a ratio of the intensity of the fluorescent dye from the cleaved BKV target sequence probes to that of the DNA-QS target probe detected throughout the PCR process.(Package insert: cobas BKV-Quantitative nucleic acid test for use on the cobas 6800/8800 Systems. Roche Molecular Systems, Inc; Doc rev 2.0, 02/2021).

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Saturday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

30 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US 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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
PBKQN BKV DNA Detect/Quant, P 32284-2
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
614567 BKV DNA Detect/Quant, P 32284-2

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Update Resources

Change Type Effective Date
New Test 2021-07-27