What is the significance of a Quantiferon (Interferon-Gamma Release Assay) result with a mitogen value of 1.20?

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Last updated: May 9, 2025View editorial policy

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From the Guidelines

A QuantiFeron mitogen value of 1.20 IU/mL is considered low and may indicate an indeterminate test result, thus it is essential to discuss these results with your healthcare provider to determine the best course of action. The mitogen serves as a positive control in the QuantiFeron-TB Gold test, and values below 0.5 IU/mL typically suggest an indeterminate result, while values above 0.5 IU/mL are generally considered adequate immune response 1. With a value of 1.20 IU/mL, your mitogen response is above the minimum threshold but still relatively low. This could potentially affect the reliability of your TB test results.

Key Considerations

  • Low mitogen responses can occur due to improper specimen handling, immunosuppression, or certain medications that affect immune function, such as TNF- antagonists 1.
  • The use of therapeutic agents that antagonize the effect of cytokine tumor necrosis factor (TNF-) has been proven to be highly effective in treating autoimmune-related conditions but may increase the risk of progression from latent TB infection to TB disease 1.
  • Yearly testing for latent TB is recommended for patients at high risk, especially those taking TNF-a inhibitors 1.

Recommendations

  • Discussing these results with your healthcare provider is crucial to determine the best course of action, which may include retesting or alternative TB testing methods such as a tuberculin skin test if appropriate.
  • Investigating underlying causes of potential immune dysfunction may be necessary, especially if you have risk factors for tuberculosis or are immunocompromised.
  • No specific medication is needed for the low mitogen value itself, but your doctor may want to proceed with caution when using the Quantiferon Gold test, especially in patients who are taking TNF-a inhibitors 1.

From the Research

Quantiferon Mitogen 1.20 Value

  • The Quantiferon mitogen 1.20 value is related to the response to mitogen in the QuantiFERON-TB gold test, which is used to diagnose latent tuberculosis infection 2.
  • A weak mitogen response, defined as an interferon-γ concentration between 0.5-2 IU/ml, has been associated with false-negative QuantiFERON-TB results in tuberculosis patients, as well as ongoing infections and worse prognosis 2.
  • The study found that decreasing mitogen response (normal, weak, and negative) was associated with increasing length of hospital stay and hospital mortality 2.
  • However, the provided studies do not specifically mention a mitogen value of 1.20, and its clinical significance is not directly addressed in the available evidence.
  • Further research would be needed to determine the clinical implications of a Quantiferon mitogen 1.20 value, as the current evidence does not provide a clear answer to this question 2.

Related Studies

  • Studies have compared the efficacy and safety of different treatments for latent tuberculosis infection, including rifampin and isoniazid 3, 4, 5, 6.
  • These studies have found that rifampin-based regimens can be effective and safe for treating latent tuberculosis infection, even in populations with certain health conditions 6.
  • However, the relationship between mitogen response and treatment outcomes is not well understood and requires further study 2.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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