MLT GlobeTuberculin skin test (Mantoux)
Infectious Diseases · also called TST, PPD test
What it measures
Measures delayed skin hypersensitivity to purified protein derivative (PPD) injected into the forearm. It screens for sensitisation to Mycobacterium tuberculosis, mainly latent TB.
Specimen and preparation
- Specimen: Intradermal injection of 5 TU PPD (no lab specimen)
- Tube: Other top
- Preparation: Read induration (not redness) across the forearm at 48–72 hours.
Reference range
| Group | Range |
|---|---|
| No risk factors | Induration < 15 mm |
| Moderate risk (health workers, high-TB-burden origin, children <4 y) | Induration < 10 mm |
| HIV, immunosuppressed, recent TB contact | Induration < 5 mm |
Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.
Causes of high values
- Latent TB infection
- Active TB (supportive only)
- Previous BCG vaccination
- Non-tuberculous mycobacterial exposure
Causes of low values
- False negative: HIV, immunosuppression, malnutrition, severe or miliary TB, recent live vaccine
Method
Mantoux intradermal technique
Good to know
Cannot separate latent from active TB; active disease needs smear, GeneXpert or culture.
Related tests
📱 Practise with a timer, track your score and earn certificates in the free MLT Globe app – Google Play or practise online.