Interpretation of the Mantoux Test
Procedure for Administering the Mantoux Test
The Mantoux test is a tuberculin skin test that helps diagnose latent tuberculosis. Results are determined by measuring the induration formed after intradermal injection of PPD.
Interpretation of the Mantoux Test
Procedure for Administering the Mantoux Test
The Mantoux test, also known as the tuberculin skin test (TST), is a diagnostic tool used to detect latent Mycobacterium tuberculosis infection. It involves the intradermal injection of purified protein derivative (PPD) and assessing the skin reaction after 48-72 hours.
Step-by-Step Administration Procedure
- Preparation: Cleanse the volar surface of the forearm and use a tuberculin syringe.
- Injection: Inject 0.1mL of PPD intradermally to produce a small wheal.
- Observation: Mark the site and instruct the patient not to scratch.
- Reading the Test: Measure the induration (not erythema) after 48-72 hours.
Interpreting the Results
The results of the Mantoux test depend on the size of the induration:
- 0-5 mm: Usually negative, but exceptions exist for immunocompromised individuals.
- 5-10 mm: May indicate exposure in high-risk patients.
- 10-15 mm: Suggests a positive result in normal-risk individuals.
- >15 mm: Definitive positive result, indicating possible tuberculosis infection.
Clinical Relevance
The Mantoux test assists clinicians in diagnosing latent TB. However, it should always be correlated with medical history and additional diagnostic tests like chest X-rays or Interferon-Gamma Release Assays (IGRA).
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