The Indian Journal of Pediatrics

, Volume 68, Issue 1, pp 53–58

Tuberculin test

Current Practice

DOI: 10.1007/BF02728860

Cite this article as:
Chadha, V.K. Indian J Pediatr (2001) 68: 53. doi:10.1007/BF02728860


Although tuberculin test is widely used for detection ot tuberculous infection among children, there is no clear understanding about its performance and interpretation. This article has been written with the purpose of elucidating the performance and interpretation of standard tuberculin test, based on the experiences gained at the National Tuberculosis Institute, Bangalore and other centres.

The standard tuberculin test involves intradermal injection of "ITU PPD RT23 with Tween 80’ on the mid-volar aspect of forearm and measurement of the maximum transverse diameter of induration after 3 days. Larger the size of induration, higher is the probability of it being due to tuberculous infection. The majority of reactions with induration size of 15 mm and above are attributable to infection with tubercle bacilli, irrespective of BCG-vaccination status. While indurations of less than 5 mm indicate absence of any kind of tuberculin sensitivity, the majority of indurations in 5–9 mm range are usually of non-tuberculous nature. An induration of 10–14 mm requires more careful interpretation. It is more likely to be attributable to infection with tubercle bacilli in case of history of contact with smear positive case or among children with clinical findings of tuberculosis. However, the size of induration in an infected child may be diminished in the presence of immuno-suppressive conditions. One should also consider the purpose of the test while interpreting the test results.

Key words

Tuberculin testSize of indurationInfection with tubercle bacilliNon-specific sensitivityBCG-inducedsensitivityPurpose of the test

Copyright information

© Dr. K C Chaudhuri Foundation 2001

Authors and Affiliations

  1. 1.National Tuberculosis InstituteBangaloreIndia