Effective April 22, 2024, Clinical Pathology Laboratories (CPL) is pleased to announce automated reflex referral for HLA-B27 results determined to be indeterminate results by flow cytometry.

Human leukocyte antigen B27 (HLA-B27) is associated with ankylosing spondylitis, Reiter syndrome and other seronegative spondyloarthropathies. The antigen is routinely assessed by flow cytometry, an antibody-based technique used to analyze and quantify specific cell markers. Alternatively, this may be assessed with PCR amplification and molecular probing of the HLA class I genes (Molecular HLA-B27 test). Flow cytometry may result as NEGATIVE or POSITIVE with rare INDETERMINATE results for signal near flow cytometry cutoff. Previously, the laboratory relied on a second antibody system to assess INDETERMINATE results; however, that confirmation system did not fully resolve INDETERMINATE results and is no longer suitable for use. For specimens received in suitable collection tubes, CPL will automatically reflex confirmatory testing by PCR with Fluorescent Probe methodology to be performed by Sonic Reference Laboratory.

Further Detail:

  • K2 EDTA anticoagulated tubes (lavender top) are suitable for flow cytometry and molecular testing and are preferred for testing.
  • Sodium heparin tubes (green top) are suitable for flow cytometry but not molecular testing. INDETERMINATE results from sodium heparin tubes (green top) will require re-collection for confirmatory testing.
  • CPT Codes
    • CPT code for Flow Cytometry HLA-B27 is 86812
    • CPT code for reflex Molecular HLA-B27 is 81374. For cases that trigger reflex molecular HLA-B27 testing, flow cytometry charges will be suppressed, and molecular charges will apply.
  • Important note: Reflex molecular HLA-B27 requires prior authorization from certain insurance companies. For accessions that trigger reflex, customer service will contact the ordering entity to initiate prior authorization.

Changes to Order Codes:

Order Code: 4864

Reporting Title: HLA-B27

Specimen Type: WHOLE BLOOD

Preferred Specimen Requirements:

  • 4 ML EDTA (LAVENDER TOP) WHOLE BLOOD.
  • CRITICAL ROOM TEMPERATURE (CRT) FOR UP TO 72 HOURS.
  • PLEASE REFER TO SPECIMEN STABILITY SPECIFICATIONS FOR MORE INFORMATION.

Acceptable Specimen Requirements:

  • 4 ML SODIUM HEPARIN (GREEN TOP) WHOLE BLOOD.
  • CRITICAL ROOM TEMPERATURE (CRT).

Minimum Specimen Volume:

  • ADULT: 2 ML WHOLE BLOOD.
  • PEDIATRIC: 1 ML WHOLE BLOOD (DOES NOT ALLOW FOR REPEAT OR ADDITIONAL TESTING).

Ref. Range and Units of Measure:

  • NOT PRESENT

Specimen Stability:

  • 3 DAYS ROOM TEMPERATURE
  • NOTE: REFRIGERATED SAMPLES ARE UNACCEPTABLE; HOWEVER, SAMPLES REFRIGERATED FOR UP TO 72 HOURS WILL BE TESTED AND RESULTS INDIVIDUALLY ASSESSED BY A PATHOLOGIST. RESULTS MAY BE REJECTED, REQUIRING SAMPLE RE-COLLECTION.

Rejection Criteria:

SAMPLES COLLECTED IN LITHIUM HEPARIN TUBE

CPT Code:

  • 86812
  • LIMITED COVERAGE TEST FOR MEDICARE.
  • ADVANCE BENEFICIARY NOTICE OF NONCOVERAGE (ABN) REQUIRED.
  • MEDICAL NECESSITY FOR TESTING WILL BE DETERMINED BY MEDICARE ADMINISTRATIVE CONTRACTOR.

LOINC: 26028-1

Order Code: 4864

Reporting Title: HLA-B27 BY FLOW RFLX

Specimen Type: WHOLE BLOOD

Preferred Specimen Requirements:

  • 4 ML EDTA (LAVENDER TOP) WHOLE BLOOD.
  • CRITICAL ROOM TEMPERATURE (CRT) FOR UP TO 72 HOURS.
  • PLEASE REFER TO SPECIMEN STABILITY SPECIFICATIONS FOR MORE INFORMATION.

Acceptable Specimen Requirements:

  • 4 ML SODIUM HEPARIN (GREEN TOP) WHOLE BLOOD.
  • CRITICAL ROOM TEMPERATURE (CRT).
  • NOTE: CONFIRMATORY TESTING CANNOT BE PERFORMED WITH SODIUM HEPARIN (GREEN TOP) RESULTS OBTAINED BY FLOW CYTOMETRY.

Minimum Specimen Volume:

  • ADULT: 2 ML WHOLE BLOOD.
  • PEDIATRIC: 1 ML WHOLE BLOOD (DOES NOT ALLOW FOR REPEAT OR ADDITIONAL TESTING).

Ref. Range and Units of Measure:

  • NOT PRESENT
  • WILL REFLEX TO HLA-B27 BY PCR ORDER CODE (3945) FOR CONFIRMATION WHEN RESULT IS INDETERMINATE. ADDITIONAL CHARGES WILL APPLY.
  • NOTE: PRIOR AUTHORIZATION IS REQUIRED BY CERTAIN INSURANCE PRODUCTS AND STATE MEDICAID PROGRAMS. PLEASE CONTACT PROVIDERS AND FOLLOW INSTRUCTIONS FOR AUTHORIZATION PRIOR TO ORDERING THIS TEST. IF AUTHORIZED, PLEASE PROVIDE DOCUMENTATION WHEN SUBMITTING THE ORDER.

Specimen Stability:

SAMPLES COLLECTED IN LITHIUM HEPARIN TUBE

  • 3 DAYS ROOM TEMPERATURE
  • NOTE: REFRIGERATED SAMPLES ARE UNACCEPTABLE; HOWEVER, SAMPLES REFRIGERATED FOR UP TO 72 HOURS WILL BE TESTED AND RESULTS INDIVIDUALLY ASSESSED BY A PATHOLOGIST. RESULTS MAY BE REJECTED, REQUIRING SAMPLE RE-COLLECTION.

Rejection Criteria:

SAMPLES COLLECTED IN LITHIUM HEPARIN TUBE

CPT Code:

  • 86812
  • LIMITED COVERAGE TEST FOR MEDICARE.
  • ADVANCE BENEFICIARY NOTICE OF NONCOVERAGE (ABN) REQUIRED.
  • MEDICAL NECESSITY FOR TESTING WILL BE DETERMINED BY MEDICARE ADMINISTRATIVE CONTRACTOR.

LOINC: 26028-1
Current New

Report Messaging for Specimens with Indeterminate Results:

If specimen is collected in an EDTA tube:

If specimen is collected in sodium heparin tube: