How to interpret the tuberculin skin test (TST) for tuberculosis

There are numerous infectious diseases in daily life, so many precautions must be taken after falling ill. Pulmonary tuberculosis (TB) is a chronic, catabolic disease transmitted via airborne droplets; *Mycobacterium tuberculosis* can persist in the human body for extended periods. How, then, is the tuberculin skin test (TST) interpreted?

Interpreting the Tuberculin Skin Test for Pulmonary Tuberculosis

The tuberculin skin test is primarily evaluated 72 hours after administration, by measuring the diameter of induration (firm swelling). Interpretation depends on the induration’s diameter and is generally categorized as negative, positive, or strongly positive. A negative result typically indicates no prior infection with *Mycobacterium tuberculosis* or no Bacillus Calmette–Guérin (BCG) vaccination; however, immunocompromised individuals may also yield false-negative results. A positive result suggests either prior TB infection or BCG vaccination. A strongly positive reaction commonly indicates active pulmonary tuberculosis in children and may suggest active disease in adults.

Patients with pulmonary tuberculosis should consume high-protein foods to bolster immunity, supplement with additional vitamins, and eat ample fresh fruits and vegetables to ensure comprehensive, balanced nutrition. According to Traditional Chinese Medicine (TCM), pulmonary tuberculosis is primarily attributed to deficiency of Lung Yin. Patients may therefore benefit from concurrently consuming certain TCM-approved, Yin-nourishing, lung-moistening foods or herbs—such as lily bulbs, silver ear fungus, schisandra berries, and pears. Steaming pears before consumption is recommended, as this reduces their inherent “cold” nature and enhances their lung-moistening effects.

Patients are advised to wear masks during routine travel and seek medical attention promptly upon noticing symptoms. We hope this information proves helpful.