Interpreting the Mantoux Test

Purpose and Significance of the Mantoux Test

The Mantoux test, also known as the Tuberculin Skin Test (TST), is a diagnostic tool used to detect Mycobacterium tuberculosis infection. It is an essential screening test in respiratory medicine.

Procedure

A small amount of purified protein derivative (PPD) is injected intradermally into the forearm. The skin reaction is assessed 48-72 hours later.

Interpreting the Results

• Negative Result: No significant induration; suggests absence of tuberculosis infection.
• Positive Result: Induration greater than predefined thresholds based on risk factors.
• False Positives & Negatives: Previous BCG vaccination or immunosuppression may affect interpretation.

Clinical Significance

The Mantoux test assists in tuberculosis screening but does not differentiate between latent and active infection. Further diagnostic tests, such as chest X-rays or sputum analysis, may be required.