Mantoux Test
990 Kshs | Home Collection Available
Synonyms
Tuberculin Skin Test, TB skin test, purified protein derivative (PPD).
Purpose
Healthcare providers perform the Mantoux Test, also known as the Tuberculin Skin Test (TST), to detect latent or active tuberculosis (TB) infection caused by Mycobacterium tuberculosis. In this procedure, they inject a small amount of purified protein derivative (PPD) intradermally just under the skin typically on the forearm.
The test helps to identify latent TB in individuals who may not show symptoms but can benefit from preventive treatment. Useful in TB screening for high-risk populations including healthcare workers, people living with HIV, and close contacts of TB patients.
The test can be done alongside Chest X-ray, Sputum Test (AFB or GeneXpert), Interferon-Gamma Release Assays (IGRA), and Ziehl-Neelsen stain (ZN stain). These additional tests help confirm active infection and determine the best course of treatment.
Patient Preparation
No special preparations required.
Samples
Collect 0.1 ml of intradermal tuberculin (PPD) injection in a Tuberculin syringe. Make an injection using a tuberculin syringe, with the needle bevel facing upward.
Reference Range
5 mm, 10 mm, or 15 mm
Results Turnaround
2 – 3 days after receipt of samples
Diseases / Diagnostic indicators
Healthcare providers interpret the Mantoux test result by measuring the size of the induration (raised, hardened area) at the injection site 48 to 72 hours after administering the tuberculin. They use the size of the reaction to determine whether the individual has been exposed to Mycobacterium tuberculosis.
Positive Test Result
A positive Mantoux test indicates TB exposure or latent TB infection. The criteria for a positive result depend on the individual’s risk factors:
≥5 mm induration is considered positive for:
- People living with HIV
- Recent close contacts of someone with active TB
- Individuals with fibrotic changes on chest X-ray suggesting old healed TB
- Organ transplant recipients
- People with immunosuppressive conditions (e.g., long-term corticosteroid therapy, end-stage renal disease)
≥10 mm induration is positive for:
- People who inject drugs
- Recent immigrants from countries with high TB prevalence (within the past 5 years)
- Healthcare workers, prison staff, or others in high-risk settings
- Mycobacteriology lab personnel
- Individuals with certain medical conditions (e.g., diabetes, cancer)
- Children under 4 years or those exposed to adults at high risk
≥15 mm induration is considered positive in:
- Individuals with no known risk factors for TB
Negative Test Result
A negative test typically means the person has not been infected with Mycobacterium tuberculosis. However, false negatives may occur in:
- Recent live-virus vaccinations (e.g., MMR)
- Early TB infection (within 8–10 weeks of exposure)
- Immunocompromised individuals
- Severe TB disease
For more on Mantoux Testing, read this study.