Which tests are commonly used to diagnose tuberculosis?

• A. Chest X-ray only
• B. Tuberculin skin test (TST), chest X-ray, and bacteriologic studies
• C. Urine analysis
• D. Blood tests alone

Answer: (B)

Diagnosing tuberculosis relies on putting together evidence from exposure testing, imaging, and microbiologic confirmation. The best approach uses tuberculin skin testing (or an IGRA) to identify prior exposure or latent infection, chest radiography to detect suggestive lung changes, and bacteriologic studies to confirm the presence of the bacteria and guide treatment.

TST or IGRA shows exposure, but not whether TB is active. A chest X-ray can support suspicion or suggest typical patterns, but radiographs aren’t definitive because other diseases can mimic TB and some active TB cases may look normal. Bacteriologic studies—smear microscopy, culture, and rapid molecular tests—provide direct evidence of Mycobacterium tuberculosis and allow drug susceptibility testing, which is essential for proper therapy.

So, combining these three components gives the most accurate diagnosis. Relying on chest X-ray alone isn’t enough, urine analysis isn’t diagnostic for TB, and blood tests alone don’t establish active TB.