Active Tuberculosis

When cough is due to Active TB, the CXR is always abnormal.

  • Suspect when findings occur in the apex, also in upper lobes.
  • Cavities are strongly suspect; nodular infiltrates too.
  • A myriad of other readings are possible.
  •  “Calcified granuloma” doesn’t count — it’s a marker for Latent TB (by definition asymptomatic).

BEWARE if radiologist finds “scars of old granulomatous disease”

  • Interpretation is impossible unless also present on a prior film, & now unchanged.
  • If no old film, consider active TB.

Diagnose Active TB by sputum tests for acid-fast bacteria (AFB).

  • The PPD isn’t helpful (20% of patients have false-negative skin tests).
  • Positive PPD identifies Latent TB (asymptomatic).

Suspect Active TB among patients at risk:

Risks for Being Infected with TB

  • Poor / Homeless
  • Born in 3rd World
  • Incarcerated / Institutionalized
  • Injection Drug User
  • Prior close contact with Active TB pt.
  • Native American / Native Alaskan
  • Staff in high-prevalence institution (most health workers are low-risk, a few are intermediate)
Risks for Reactivating TB

  • HIV-infected
  • Dialysis
  • Silicosis
  • Diabetes (poorly-controlled)
  • Immunosuppressive Meds (chronic steroids, organ transplant, TNF-Inhibitors)
  • Chronic Illnesses causing Malnutrition
  • Children <4 y.o.
  • Initial TB infection within last 2 years