Lab marker · Low

Low QuantiFERON-TB (interferon-gamma release assay): what it means

A QuantiFERON-TB (interferon-gamma release assay) result below the normal range is considered low. Here is what a reduced QuantiFERON-TB (interferon-gamma release assay) can point to, and when it is worth discussing with a doctor.

Reference range: Reported as negative, positive or indeterminate; negative is the expected result — a positive indicates infection with the TB bacterium (usually latent, dormant TB), and does not by itself distinguish latent from active disease, which needs a chest X-ray and clinical assessment

Understand your full result

What a low QuantiFERON-TB (interferon-gamma release assay) can mean

  • Negative — the expected result; no evidence of TB infection.
  • A recent exposure — the test can be negative very soon after contact, before the immune response develops, so it may be repeated after a window.
  • A weakened immune system — can occasionally give a false-negative or indeterminate result.

When to discuss with a doctor

This TB blood test is used to detect latent TB infection — commonly when screening people at higher risk (close contacts of someone with TB, people from higher-incidence regions, healthcare workers) and, importantly, before starting treatments that suppress the immune system, which can reactivate dormant TB. A positive result usually means latent, dormant infection and prompts a chest X-ray and clinical review to rule out active disease; if latent, a course of treatment may be offered to prevent it becoming active later. A positive test with symptoms such as a persistent cough, fevers, night sweats or weight loss needs prompt assessment for active TB, which is contagious and treatable. Mediora.AI shows the TB test result alongside relevant markers so it is read in context; interpreting a positive result and deciding on treatment belong with your doctor.

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.