Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Quantiferon is an ELISA based interferon gamma release assay. Whole blood is stimulated overnight with Mycobacteria Tuberculosis (TB) specific antigens, positive control or a nil control. Interferon gamma concentration from the plasma is measured by ELISA. This test is particularly suitable for screening large numbers of healthy people in contact tracing or health care worker screening. This test is not suitable for patients on immunosuppressive drugs or have an immunodeficiency. Quantiferon assay cannot distinguish between latent and active TB infection.
Special Quantiferon collection tubes are required for this test.
Samples must not be refrigerated.
Specimen container paediatric:
Blood in 4 Specific Quantiferon Gold collection tubes
Specimen container adult:
Blood in 4 Specific Quantiferon Gold collection tubes
Minimum volume paediatric:
Exactly 1 ml in each bottle
Minimum volume adult:
Exactly 1 ml in each bottle
Special requirements:
Patients’ blood should be collected in the 4 Quantiferon blood tubes – Negative Control (Grey), TB1 (Green), TB2 (Yellow) and Mitogen (Purple).
Each of tube must contain 1ml of blood (Lithium Heparin (3 tubes, 1ml in each) or Quantiferon (4 Tubes, 1ml in each). More or less than 1ml renders the test inaccurate; such samples will not be tested and repeat samples will be requested.
The samples must arrive within 16 hours of venepuncture otherwise the test should not be performed.
Sample stability:
THE SAMPLE MUST NOT BE REFRIGERATED and must be submitted to the laboratory by 4pm on the day on which it is drawn.
Transport requirements:
Before 4pm:
Once collected, Quantiferon Gold samples must be submitted to the laboratory by 4pm on the day on which it is drawn. If the collection time is approaching this deadline, the sending department should inform lab staff of the imminent arrival of these samples so we can look out for their arrival. The direct telephone number for the TB laboratory is 0191 213 8787. A call should also be made to the Blood sciences reception area if the sample is being collected or dropped off at the RVI. The direct line is 24718 Option 1.
After 4pm:
If the sample is taken after this cut off it may still be possible to send. Please communicate with the MV laboratory in the first instance. The sample will need to be sent directly to MV at FH using a hot car or blood bike. The sending dept. must arrange this by contacting the Transport Team on ex 31818 to make an urgent Hot Car request. The MV laboratory must be made aware of the arrangement so they can support the receipt of this samples out of core hours.
Until the sample is received in the MV department, we have little control over the sample.
Add On Test:
N/A
Quality Assurance:
External Quality Assurance Scheme: INSTAND.
Interpretation:
Positive threshold >0.35 IU/mL
Reference Ranges:
None available
Factors affecting result:
Ensure QuantiFERON tubes are at room temperature before filling. This test cannot be refrigerated, please therefore ensure that there is sufficient time for submission to the laboratory
Referenced Documents:
UK SMI B 40: investigation of specimens for Mycobacterium species
Other Info:
N/A