QuantiFERON-TB Gold Blood Collection
Blood for the QuantiFERON-TB Gold test must be collected in heparinized vacutainer tubes. 1
Specific Collection Requirements
Anticoagulant Type
- The test requires fresh heparinized whole blood for proper interferon-gamma (IFN-γ) detection 1
- The heparin anticoagulant preserves white blood cell function, which is essential since the test measures IFN-γ released by sensitized T-cells after antigen stimulation 1
Collection Methods
Two FDA-approved collection approaches exist:
- Direct collection into specialized QFT tubes (containing heparin plus specific antigens) - this is the traditional "in-tube" method 1
- Collection into lithium heparin tubes with subsequent transfer to test tubes 2, 3
Critical Timing Constraint
- Blood must be incubated with test antigens within 12 hours of collection 1
- This tight timeframe is non-negotiable because delayed processing compromises white blood cell viability and test accuracy 1
Important Practical Considerations
Why Heparin Specifically
- Heparin anticoagulation maintains cellular integrity without interfering with the immune response measurement 1
- Other anticoagulants (EDTA, citrate) are not appropriate as they can affect lymphocyte function
Collection Method Performance
- The lithium heparin transfer method shows higher indeterminate rates (up to 4%) compared to direct tube collection (<1%) 3
- However, the transfer method offers greater flexibility for clinics without immediate access to specialized QFT tubes 2, 3
Common Pitfall
The most critical error is delayed processing beyond 12 hours, which invalidates the test regardless of proper tube selection 1. Ensure your laboratory can process specimens within this window before drawing blood.