Adult Health Practice Exam 2026 – Complete Study Resource

A 15 mm induration is considered a concerning response to a tuberculin skin test (TST) for a non-HIV client because it typically indicates a positive result for tuberculosis (TB) infection. The interpretation of the TST depends on several factors, including the individual's risk factors and medical history.

For individuals who are at average risk for TB, a 15 mm or greater induration is positive, highlighting a significant immune response to the TB antigens injected during the test. This indicates a higher likelihood of TB infection, warranting further evaluation and potentially treatment.

In contrast, a 5 mm induration is considered positive in individuals with a compromised immune system, recent exposure to TB, or other specific high-risk factors, while an 8 mm induration falls into a borderline category, often requiring additional clinical context or follow-up. Having no response at all does not suggest the presence of TB specifically, though it may indicate other issues such as test administration or reading errors. Therefore, the presence of a 15 mm induration is a clear signal in the clinical context that must be addressed promptly.