Active TB should be suspected based on a combination of epidemiological (eg, exposure, travel to, or residence in a high prevalence area, history of prior TB), clinical (eg, cough lasting 2-3 weeks or longer, fever, night sweats, weight loss, fatigue, less commonly, chest pain, dyspnea, and hemoptysis), chest radiograph abnormalities (eg, infiltrates, fibrosis, cavitation), and histopathologic (eg, caseating granuloma)¹.

Among HIV-negative patients, the highest prevalence of TB is found those who have been incarcerated, use intravenous drugs, have alcohol use disorder, or are immunocompromised (including diabetes mellitus)^2,3. 

Patients suspected of TB based on clinical criteria should undergo chest radiography.  Reactivation pulmonary TB (~90% of TB in adults) classically presents with upper lobe and/or the superior segment of the lower lobe disease.  Remember that up to 5% of patients with active pulmonary TB have normal chest radiograph, however⁴.  

All hospitalized patients suspected of having active TB should be placed on appropriate isolation precautions until TB is excluded.

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References

1. Sia IG, Wieland ML. Current concepts in the management of tuberculosis. Mayo Clin Proc. 2011;86:348-361. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068897/
2. Center for Disease Control. Tuberculosis: Data and Statistics. https://www.cdc.gov/tb/statistics/default.htm. Accessed October 3, 2016.
3. World Health Organization. Tuberculosis. http://www.who.int/mediacentre/ factsheets/fs104/en/. Accessed October 3, 2016.
4. Marciniuk, D, McNab, BD, Martin WT, Hoeppner, VH. Detection of pulmonary tuberculosis in patients with a normal chest radiograph. Chest 1999;115:445-452. https://journal.chestnet.org/article/S0012-3692(15)50590-4/abstract

Contributed by Charles C. Jain MD, Medical Resident, Massachusetts General Hospital