Test Directory
TB Quantiferon Gold 4 tube Assay
Containers - Adult
TB Quantiferon 4 tube Assay
|
Volume Range
0.8 - 1.0 ml |
Containers - Child
|
TB Quantiferon 4 tube Assay
|
Volume Range
0.8 -1.0 ml |
Laboratory Site
Old Dalkeith Road
Edinburgh
EH16 4SA
Transport arrangements
Utility: Quantiferon Gold is an interferon gamma release assay. They are only useful to identify latent (non-active) TB infection. IGRAs measure interferon gamma released from sensitised cells on exposure to PPD. They are a measure of prior infection with MTB. They are more sensitive than the TB skin test as they are specific to certain antigens so don't respond to previous BCG vaccination or most non-tuberculous mycobacteria.
However it can't:
- Rule in active TB (not specific enough)
- Rule out active TB (not sensitive enough)
- Differentiate between active and latent infection (positive in both)
- Risk stratify likelihood of developing active TB in latent infection
- Be used to assess treatment
Please see Respiratory TB Guidance for further information.
Inter-site van shuttle service, GP van service, External hospital van service, Couriers, Hospital porter collection (refer to collection times posted in wards / departments), Hospital Pneumatic Tube System (PTS)
Sample storage arrangements
Specimen transport arrangements must be in accordance with current postal and transport regulations. Samples should be transported to the laboratory without delay. If processing is delayed, store at room temperature. Patient samples can be transported at ambient temperature. Samples must be received into the lab within 16 hours of being taken.
When samples are taken at Western General Hospital (WGH) or St John's Hospital (SJH), please deliver samples directly to your local laboratory where they will be incubated and then transferred to the Royal Infirmary of Edinburgh (RIE).
Special instructions for collection
To order tubes via PECOS the product number is 622222.
Gently invert each tube 10 times. Samples should reach laboratory within 16 hours of being taken. Alternatively, samples should be incubated upright at 37oC +- 1 for 16-24 hours. After incubation, samples may be held between 4 and 27oC for up to 3 days prior to centrifugation.
Clinical samples must be collected into leak-proof containers and placed into a sealed bag with absorbent material. Patient samples must be individually packaged and not mixed with other patient samples. Any appropriate hazard labelling should be clearly visible on the sample bag / sample.
How to request
Via Trak ("Quantiferon Gold") or by request form. Forms must be fully completed with Patient Identifier Number (CHI), Forename, Surname, Date of Birth, Gender and Location of patient (hospital and ward or primary care centre).
Availability
Samples can be received into the Blood Sciences lab on any NHS Lothian site, which are open 24/7. They will then be transported to the testing site after the samples have been stabilised for processing.
Anticipated turnaround
10 days
What happens if the result is positive or abnormal
Positive results are notified to the TB Bacteriologist and are available in the patient’s records.
Static information/disclaimer
False negative results may occur for a variety of reasons including: inappropriate timing of sample collection, inappropriate sample type, inappropriate sample storage and incorrect volume of blood in each Quantiferon collection tube. New and emerging variants may also occur which may not be detected by specific assays. Towards the limit of detection of an assay sampling variation will result in lower reproducibility. Haemolysed or lipaemic samples can also cause interference with assay results.
General additional information
Only indicated for diagnosis of latent TB infection.