Tuberculin test can be read after 24 hours in adolescent children.

Objective: To assess readability of 24-h tuberculin response in adolescent school children.

Design: Prospective observational study in school.

Subjects: 601 healthy adolescent children.

Interventions: Tuberculin (1TU PPD RT23 Tween80) was administered and indurations at 24 and 72 h were compared.

Main Outcome Measure: Tuberculin reaction at 24 h.

Results: One hundred twelve children (18.6%) had a positive tuberculin reaction. Prevalence of tuberculin positivity was least (14.2%) in the 10-year age-group and maximum in the 13-year age-group (21.2%). When individual values of tuberculin reaction at 24 and 72 h were compared, a significant difference was noted irrespective of the tuberculin status (t = 8.46, p = 0.001). However, when tuberculin reaction was considered as positive or negative, this difference was not significant (t = 1.89, p > 0.05).

Conclusions: Tuberculin status in adolescents can be read as positive or negative at 24 h, irrespective of their bacillus Calmette-Guérin scar status.