Correlation between levels of tumour necrosis factor-alpha and levels of pH, glucose, and lactate dehydrogenase in parapneumonic effusions.

OBJECTIVES: This study was undertaken to investigate the correlation, which has not been previously investigated, between levels of tumour necrosis factor-alpha (TNF) and levels of pH, glucose, and lactate dehydrogenase (LDH) in pleural fluid of patients with uncomplicated parapneumonic effusion (UCPPE), and patients with complicated parapneumonic effusion (CPPE).

METHODS: Using a commercially-available high sensitivity ELISA kit, levels of TNF were measured in pleural fluid of patients with UCPPE (n = 23), and CPPE (n = 15), and were compared with levels of pH, glucose, and LDH in these two groups.

RESULTS: The mean +/- SD values of pleural fluid TNF, pH, glucose, and LDH in the UCPPE group were 11.05 +/- 7.65 pg/ml, 7.41 +/- 0.08, 125 +/- 48 mg/dl, and 306 +/- 182 IU/l, respectively. In the CPPE group the values were 56.07 +/- 28.5 pg/ml, 6.82 +/- 0.25, 42 +/- 36 mg/dl, and 2096 +/- 1916 IU/l, respectively. The only significant correlation, which was negative, was found between levels of TNF and pH in the CPPE group (r = -0.62, P = 0.01). Levels of pleural fluid TNF and LDH were significantly higher, and levels of glucose were significantly lower in the CPPE group than in the UCPPE group (P < 0.0001).

CONCLUSIONS: This study demonstrates, for the first time that TNF levels correlate inversely with levels of pH in pleural fluid of patients with CPPE but not of patients with UCPPE. This correlation may, in part, explain the pathophysiology of the pleural complications which occur in the presence of CPPE.