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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: BK Virus, Quantitative by PCR


CPT Code(s): 87799

Methodology: Real-Time PCR

Clinical Significance: Detect and quantitate BK virus in blood.

Days Performed: Mon-Fri.

Turnaround Time: Stat: Not available stat.
Routine: 2 - 3 days.

Specimen Requirements

Specimen: Blood

Collection Container: Preferred: Lavender top
Also Acceptable: K2EDTA Plasma Preparation Tube (PPT)

Collection Volume: Preferred: 6 mL
Pediatrics: 2 mL

Sample Analyzed: Plasma

Volume Required: Preferred: 3 mL
Pediatrics: 1.2 mL

Specimen Processing: For optimal specimen, separate cell-free plasma from whole blood and transfer plasma to a sterile polypropylene tube within 6 hours of collection. Freeze plasma at -60 to -80C (preferred). Prior to freezing at -60 to -80C, EDTA plasma may also be stored at either 2 to 8C for up to 72 hours or frozen at -20C for up to 7 days.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220) immediately. If frozen, transport separated plasma on dry ice and keep frozen.

Outreach Specimen Transport: Transport whole blood or separated plasma at room temperature to UWHC Core Laboratory (B4/220) using priority overnight delivery only.

Unacceptable Criteria: LIMIT: One specimen every 48 hours.

Stability: Ambient: 3 days
Refrigerated: 3 days
Frozen: Whole blood- Not acceptable; Plasma-indefinitely at -70C or 7 days at -20C.


Expected Results:

Not detected


The reported concentration of BK virus particles in blood may indicate viremia levels and treatment efficacy.

Test Limitations:

Analytical measurement range for this test is 250-10,000,000 copies/mL (2.40-7.00 log10 copies/mL) of plasma. Detection range is 50 to unlimited copies per mL of plasma.

Additional Information:

For plasma samples in which BKV DNA is detected between the analytical measurement range (AMR) of 250-10,000,000 copies/mL (2.40-7.00 log10 copies/mL), a quantitative value (copies/mL) will be reported. If BKV DNA is detected outside the analytical measurement range (AMR) a result of <250 copies/mL or >10,000,000 copies/mL will be reported. If BKV DNA is not detected, a result of "Not detected" will be reported.  A result of "not detected" does not rule out the presence of BKV DNA or the absence of infection.  False negative results may be due to the suppression of viral replication to levels below the detection threshold, or to inhibitory substances that may be present in the specimen.  Inadequate specimen collection, processing and storage may invalidate test results.  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.  DNA sequence polymorphisms in BKV strains may underestimate viral levels.  The presence of variation in BKV DNA sequences are monitored in the real-time PCR assay.  This assay does not genotype the virus, and consequently does not provide any information with regard to BKV drug resistance. 


The performance characteristics of this test were validated by UWHC Clinical Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test; however, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. The UWHC Clinical Laboratories is authorized under Clinical Laboratory Improvement Amendments (CLIA) to perform high-complexity testing.


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