CRP and empyema: Pleural fluid CRP proved to be an excellent marker for distinguishing parapneumonic effusion from malignancy (cut-off value ≥49.2 mg/dl, 75% sensitivity, and 85.7% specificity) and parapneumonic plus empyema from tuberculous effusion plus malignant effusion (cut-off value ≥47.4 mg/dl, 84.6% sensitivity, and 90.8% specificity).