In a Tuberculin skin test, induration indicates what and is measured in what unit?

In a Tuberculin skin test, induration indicates what and is measured in what unit?

• A. Erythema indicates a positive reaction and is measured in millimeters
• B. Induration indicates a positive reaction and is measured in millimeters
• C. Induration is measured in meters and indicates a negative reaction
• D. Erythema indicates a negative reaction and is measured in centimeters

Answer: (B)

In a tuberculin skin test, the reaction you look for is induration—the firm, raised area at the injection site. This induration indicates a positive reaction, and its size is measured in millimeters. Erythema (redness) is not used to determine positivity. Measurements in meters or centimeters would be incorrect. Reading is typically done 48–72 hours after the injection.

In a tuberculin skin test, the reaction you look for is induration—the firm, raised area at the injection site. This induration indicates a positive reaction, and its size is measured in millimeters. Erythema (redness) is not used to determine positivity. Measurements in meters or centimeters would be incorrect. Reading is typically done 48–72 hours after the injection.