[Diagnostic value of pleural fluid and serum procalcitonin levels in the diagnosis of parapneumonic pleural effusion].

INTRODUCTION: To determine the diagnostic value of pleural fluid procalcitonin (PF-PCT) and serum PCT (S-PCT) levels in the diagnosis of parapneumonic pleural effusion (PPPE).

MATERIALS AND METHODS: Sixty five inpatients with exudative pleural fluid were consecutively included in this prospective study. Biochemical (total protein, albumin, LDH, glucose, pH, PCT) studies were performed in concurrently obtained pleural fluid and venous blood samples, cytologic and microbiologic (acid-fast bacillus smear/culture, nonspecific bacterial Gram stain/culture, fungal culture) studies were performed in pleural fluid. The patients were grouped as PPPE (n= 33) and non-PPPE (n= 32) after the diagnoses were definitely established.

RESULTS: A total of 65 patients (M/F: 38/27; age: 57.53 ± 18.46 years) with exudative pleural fluids were assessed. In the 33 with PPPEs, 6 simple PPPEs, 5 complicated PPPEs and 22 empyemas were determined whereas in the 32 non-PPPEs, 9 tuberculous, 10 malignant, 6 paramalignant, 5 non-specific effusions and 2 chylothoraces were determined. Compared with the non-PPPE group, more fever, pneumonic infiltrations and fluid loculation, higher sedimentation, leukocyte, fluid LDH besides lower fluid glucose, pH, albumin and protein together with lower serum LDH were determined in the PPPE group (p< 0.05). Higher PS-PCT (1.03 ± 1.27 vs. 0.06 ± 0.06 ng/mL) and S-PCT levels (0.90 ± 1.44 vs. 0.05 ± 0.02 ng/mL) were determined in the PPPE group (p= 0.000). In the PPPE group, PS-PCT and S-PCT showed positive correlation with each other while PS-PCT did with sedimentation, leukocyte, CURB-65 and serum LDH, and S-PCT did with sedimentation, CURB-65 and duration of hospitalization. ROC curve, a specificity of 96.9% and a sensitivity of 57.5% were determined for an optimal PS-PCT cut-off level (0.285 ng/mL), and a specificity of %96.9 and a sensitivity of %66.6 for an optimal S-PCT cut-off level (0.105 ng/mL) that could differentiate PPPE.

CONCLUSION: PS/S-PCT levels were found to be highly efficient in excluding PPPE but not sufficiently reliable in the diagnosis of it. However, these findings should be reassessed in a larger group of cases that have not been given any antibiotic/anti-inflammatory treatment.