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Test ID TRECS T-Cell Receptor Excision Circles Analysis, Blood

Additional Testing Requirements

This assay is useful for evaluating thymic output, and for longitudinal assessment of thymic function.


For comprehensive assessment of thymic function in pediatric patients and/or individuals who have received hematopoietic stem cell transplantation, order this test together with CD4RT / CD4 T-Cell Recent Thymic Emigrants, Blood.

Shipping Instructions

Specimens must be received in the laboratory on weekdays and by 4 p.m. on Friday. Collect and package specimen as close to shipping time as possible.


It is recommended that specimens arrive within 24 hours of collection.


Samples arriving over the weekend or on observed holidays may be canceled.

Necessary Information

Ordering physician's name and phone number are required.


TREC Assay Patient Information (T589) is required. Testing will proceed without the form; however, results will be held under the information is received.

Specimen Required

For serial monitoring, it is recommended to perform specimen collection at the same time of day, if possible.

Supplies: Ambient Shipping Box-Critical Specimens Only (T668)

Container/Tube: Lavender top (EDTA)

Specimen Volume:

Adults: 10 mL


-Preferred volume for >1 year: 5 mL

-Preferred volume for ≤1 year old: 3 mL

Collection Instructions:

1. Do not collect specimen using a butterfly needle.

2. Send whole blood specimen in original tube. Do not aliquot.


TREC Assay Patient Information (T589) is required

Useful For

Measuring T-cell output or reconstitution (thymopoiesis) following hematopoietic cell transplantation or highly active antiretroviral therapy


Evaluating thymic function in patients with cellular or combined inborn errors of immunity (formerly primary immunodeficiencies), or receiving immunotherapy or cancer vaccines


Assessing T-cell recovery following thymus transplants for DiGeorge syndrome

Special Instructions

Method Name

Real-Time Quantitative Polymerase Chain Reaction (PCR)

Reporting Name

TREC Analysis, B

Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

Adults: 10 mL
Pediatrics: 1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Ambient 48 hours PURPLE OR PINK TOP/EDTA

Reference Values

The appropriate age-related reference values will be provided on the report.

Day(s) Performed


Report Available

6 to 8 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

81479-Unlisted molecular pathology procedure

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TRECS TREC Analysis, B In Process


Result ID Test Result Name Result LOINC Value
615825 TREC Copies 62320-7
615822 CD3 T Cells 8122-4
615823 CD4 T Cells 24467-3
615824 CD8 T Cells 14135-8
616642 Previous Run Date 93126-1
616646 Previous run TREC Copies 93126-1
616643 Previous run CD3 T Cells 93126-1
616644 Previous run CD4 T Cells 93126-1
616645 Previous run CD8 T Cells 93126-1
615826 Interpretation 69047-9
615827 Additional Information 48767-8
615828 Method 85069-3
615829 Disclaimer 62364-5
615830 Released By 18771-6