The effect of pleural fluid content on the development of pleural thickness.

SETTING

Residual pleural thickness (RPT) is a common complication of tuberculous pleurisy (TP), and the degree of RPT cannot be predicted in advance.

OBJECTIVES

To determine whether pleural fluid content has an effect on the development of RPT.

DESIGN

Forty-seven patients with TP were enrolled in the study. A set of biochemical tests: lactate dehydrogenase, glucose, total proteins, adenosine deaminase, tumour necrosis factor alpha (TNF-alpha), alpha-1 acid glycoprotein (AAG), alpha-2 macroglobulin, C-reactive protein (CRP), complement 3 and complement 4 were studied in the pleural fluid samples. After 6 months of anti-tuberculosis treatment, patients were re-evaluated for RPT. RPT was defined in a posteroanterior chest radiograph as a pleural space of >2 mm or >10 mm measured in the lower lateral chest at the level of an imaginary horizontal line intersecting the diaphragmatic dome.

RESULTS

Seventeen patients (36.17%) had an RPT of <2 mm, 18 (38.29%) had an RPT of 2-10 mm, and 12 (25.53%) had an RPT of >10 mm. TNF-alpha levels were lower in patients with an RPT of <2 mm than in patients with an RPT of 2-10 mm or >10 mm (P < 0.05 and P < 0.01, respectively). The level of TNF-alpha was higher in patients with an RPT of >10 mm compared to the 2-10 mm group (P < 0.05). Meanwhile, pleural fluid glucose, AAG and CRP concentrations were significantly higher in patients with an RPT of >10 mm than in patients with <2 mm RPT (P < 0.05, P < 0.01, and P < 0.05, respectively).

CONCLUSION

In TP, the development and degree of RPT are significantly correlated to the glucose, CRP, AAG, and TNF-alpha levels in the pleural fluid.