TABLE 1.

Interpretation of tuberculin skin test (TST) results: American guidelines

TSTs should be read at 48 to 72 h after placement

Induration more than 5 mm

Children in close contact with known or suspected contagious cases of tuberculosis disease

Children suspected to have tuberculosis disease: – Chest radiograph consistent with active or previously active tuberculosis – Clinical evidence of tuberculosis disease

Children receiving immunosuppressive therapy or with immunosuppressive conditions, including human immunodeficiency virus infection

Induration more than 10 mm

Children at increased risk of disseminated disease: – Young age (younger than four years) – Other medical conditions, including Hodgkin disease, lymphoma, diabetes mellitus, chronic renal failure or malnutrition

Children with increased risk of exposure to tuberculosis disease: – Born or whose parents were born in high-prevalence regions of the world – Frequently exposed to adults who are infected with human immunodeficiency virus, homeless, users of illicit drugs, residents of nursing homes, incarcerated or institutionalized, and migrant farm workers – Travel and exposure to high prevalence regions of the world

Induration less than 15 mm

Children four years of age or older without any risk factors

Data from reference 1