Utility of pleural fluid glucose measurement in TB pleural effusions

Abstract

Background: Tuberculous pleural infection is the most common form of extrapulmonary TB infection. Pleural fluid glucose has been used to aid diagnosis of bacterial pleural infections including TB however the data for its utility in pleural TB is limited. Aim: To identify the utility of pleural fluid glucose as a biomarker in the diagnosis of TB pleural infections. Methods: We conducted a retrospective case series collection of 106 patients diagnosed with pleural Tuberculosis at a tertiary pleural service from 2010 to 2019. All patients received treatment for TB as per UK national guidelines adjusted to culture sensitivities. Results: 106 patients were initially included, with 12 excluded due to insufficient data. A total of 64/94 patients had pleural fluid sent for glucose measurement. All but 2 patients had a pleural fluid glucose less than 7mmol/L. 39/64 (61%) patients had a pleural fluid glucose ranging 4.1-6.0mmol/L and 20/64 (31%) patients had a pleural fluid glucose of Conclusion: Pleural fluid glucose appears to be low in patients who are pleural fluid or biopsy culture positive, however it is not significantly lower when compared to all patients with TB pleural infection. Therefore unlike in other bacterial pleural infections, we suggest that pleural fluid glucose may not be a useful marker in aiding the diagnosis of pleural TB infection.