If a Mantoux test shows 7 mm induration in a high-risk patient, is this considered positive?

If a Mantoux test shows 7 mm induration in a high-risk patient, is this considered positive?

• A. No
• B. Yes
• C. Only if symptoms present
• D. Only if initial chest X-ray is abnormal

Answer: (A)

Interpreting a Mantoux test depends on the person’s risk category. For someone considered high risk, a positive result is typically defined as 10 mm or more of induration. A 7 mm induration does not meet that threshold, so it is not considered positive. The presence of symptoms or an abnormal chest X-ray does not by itself make the skin test positive; those factors guide further evaluation if TB is suspected. (In the very highest risk groups, such as those with HIV, the positive cutoff can be 5 mm, but for general high-risk individuals, 10 mm is the standard threshold.)

Interpreting a Mantoux test depends on the person’s risk category. For someone considered high risk, a positive result is typically defined as 10 mm or more of induration. A 7 mm induration does not meet that threshold, so it is not considered positive. The presence of symptoms or an abnormal chest X-ray does not by itself make the skin test positive; those factors guide further evaluation if TB is suspected. (In the very highest risk groups, such as those with HIV, the positive cutoff can be 5 mm, but for general high-risk individuals, 10 mm is the standard threshold.)