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Test Code QFT TB Testing by Quantiferon-Gold TB, LAB2820

Performing Laboratory

St. Luke's Hospital, Cedar Rapids, Iowa

Specimen Requirements

QFT-Plus Blood Collection Tubes

  1. QFT-Plus Blood Collection Tubes can be obtained from St. Luke's Laboratory and should be stored at room temperature and tubes should be at room temperature at the time of collection.
  2. Collect 1 mL of blood by venipuncture directly into each of the QFT-Plus Blood Collection Tubes.
    • The tubes draw blood relatively slowly, keep the tube on the needle for 2-3 seconds once the tube appears to have completed filling.
    • The black mark on the side of the tubes indicates the validated range of 0.8 to 1.2 mL.  If the level of blood in any tube is outside of the indicator mark, a new blood sample should be obtained.
    • If a butterfly needle is used, a "purge" tube should be used to ensure that the tubing is filled with blood prior to the QFT-Plus tubes.
  3. Immediately after filling the tubes, shake them 10 times just firmly enough to make sure the entire inner surface of the tube is coated with blood.
  4. Do not centrifuge.

 

Lithium Heparin Dark Green-top Tubes

  1. Tubes should be at room temperature at time of collection.
  2. Fill 3 lithium-heparin dark green-top tubes and gently mix by inverting the tubes several times.
  3. Minimum requirement is 5 mL of whole blood.
  4. Prior to refrigeration, tubes should be held at room temperature between 15 minutes to 3 hours after collection.
  5. Do not centrifuge.

Reference Values

Negative

Day(s) Test Set Up

Monday - Friday

Useful For

Indirect test for Mycobacterium tuberculosis infection, to be used in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations.  This test is not recommended for use for diagnosis of active tuberculosis infection.

Methodology

Chemiluminescence Immunoassay

Test Classification and CPT Coding

86480

Report Available

48-96 hours upon collection

Transport

QFT-Plus Blood Collection Tubes

Option 1: Incubation at testing laboratory

  1. Transport QFT-Plus tubes at 2-27⁰C within 16 hours of collection.
  2. If tubes cannot be sent within 16 hours, see alternative directions for lithium heparin tubes.

Option 2:  Incubation at blood collection site

  1. If tubes are not incubated immediately after blood collection, remix tubes by inverting 10 times immediately prior to incubation.
  2. Incubate tubes UPRIGHT at 37⁰C for 16-24 hours.
  3. After incubation, tubes may be held between 4-27⁰C for up to 3 days prior to centrifugation at the testing laboratory.
  4. Preferably, prior to transport, specimens are spun for 15 minutes at 4000-5000 RPM.

 

Lithium Heparin Dark Green-top Tubes

  1. Transport the tubes at 2-8⁰C within 48 hours of collection.
  2. Tubes should not be centrifuged.