From the Research
The average white blood cell (WBC) count in tuberculosis pleural effusion typically ranges from 500 to 2,500 cells/μL, with lymphocytes predominating (usually >50% of cells) 1.
Key Characteristics of Tuberculous Pleural Effusion
- The fluid is generally exudative with protein levels >3 g/dL and pleural fluid to serum protein ratio >0.5.
- While early in the disease neutrophils may briefly predominate, the characteristic finding is lymphocytic predominance.
- The pleural fluid glucose concentration is usually normal or only slightly decreased, and the pH is typically >7.30.
- Adenosine deaminase (ADA) levels above 40 U/L in pleural fluid strongly suggest tuberculosis, especially in high-prevalence areas.
Diagnosis and Treatment
- Definitive diagnosis requires demonstration of Mycobacterium tuberculosis in pleural fluid or tissue, though culture positivity rates are relatively low (less than 30%) and may take weeks.
- Pleural biopsy showing granulomatous inflammation significantly increases diagnostic yield.
- Treatment regimens are identical to those administered for pulmonary TB, with multidrug therapy remaining the treatment choice 1.
Important Considerations
- In regions of medium and high disease prevalence, ADA, interferon gamma (IFN-γ), and interleukin 27 (IL-27) dosages are useful to establish presumptive diagnosis in patients with compatible clinical/radiological picture who present with lymphocytic pleural effusion.
- Molecular tests present low sensitivity in pleural fluid, being useful for diagnostic confirmation 1.