TST Interpretation: Positivity thresholds vary by risk group. Measure induration (swelling), NOT erythema.
High Risk (≥5mm threshold)
HIV+, recent contact w/ active TB, or immunosuppressed.
Moderate Risk (≥10mm threshold)
Recent immigrants, IVDU, congregate setting staff/residents, or children <4y.
Low Risk (≥15mm threshold)
Patients with no known risk factors for TB.
Interpretation Result
Indicates TB infection at the 5mm threshold for this risk group. Rule out active disease (CXR/Symptoms).