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Test Code XTBPB T-SPOT TB Test (Patient)

Additional Codes

EPIC:  LAB11891

For Hospital employees, order Sunquest code XTBSB; EPIC code:  LAB11892

Methodology

ELISA-based Interferon Gamma Release Assay

Performing Laboratory

Oxford Diagnostic Laboratories

Specimen Requirements

Heparinized Whole Blood.  Collect whole blood in lithium or sodium heparin tubes (green top), as follows:

 

Adults and children > 10 yrs - One 8 ml tube or two 4 ml tubes

Children 2 yrs to < 10 yrs - One 4 ml tube

Children up to 2 yrs - One 2 ml pediatric tube

 

Store collected blood at room temperature (18-25°C).

Do not refrigerate or freeze.

EDTA tubes (Purple top) are NOT ACCEPTABLE

Reference Values

Negative

Day(s) Test Set Up

Monday - Friday only

Do not collect specimens on weekends and holidays.

Clinical Information

The T-SPOT test is an indirect test for latent Mycobacterium tuberculosis infection, to be used in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations. 

Latent tuberculosis infection (LTBI) is a noncommunicable, asymptomatic condition that persists for many years in individuals and may progress to active tuberculosis disease, particularly in immunosuppressed patients. The primary goal for diagnosis of LTBI is to initiate medical treatment in order to prevent progression to active disease. Historically, detection of LTBI has been done using the tuberculin skin test (TST). The TST has certain limitations however, including subjective interpretation, limited sensitivity in immunosuppressed patients, and the possibility of false-positive results in individuals who have received the Bacille Calmett-Guerin (BCG) vaccine or are infected with other mycobacteria.  Interferon gamma release assays avoid these limitations by directly assessing the cell-mediated immune response to Mycobacterium tuberculosis complex antigens, providing an objective endpoint.