Pleural fluid procalcitonin to distinguish infectious from noninfectious etiologies of pleural effusions

In this study we investigate the diagnostic value of pleural fluid procalcitonin (PCT) in distinguishing infectious and noninfectious etiologies of pleural effusion. We reviewed the medical records of 75 hospitalized patients who underwent thoracentesis between 2011 and 2012. Data on pleural fluid lactate dehydrogenase (LDH), protein, albumin, cell count and differential, pH, Gram stain and culture, cytology, triglyceride, cholesterol, amylase, and PCT were collected. Data on serum LDH, protein, albumin, prothrombin time, normalized, and blood culture were also collected. Pleural effusions were classified into 2 groups, infectious and noninfectious. There were 18 infectious pleural effusions (IPE) and 57 noninfectious pleural effusions (NIPE). Median pleural fluid PCT was 1.088 ng/mL (0.312-2.940 ng/mL) in IPE and 0.123 ng/mL (0.05-0.263 ng/mL) in NIPE, with a P value < 0.0001. Pleural fluid PCT > 0.25 ng/mL had a sensitivity of 77.78% and specificity of 74.14% for diagnosing an IPE. A subgroup analysis of PCT in exudative infectious effusions versus exudative noninfectious malignant/paramalignant effusions showed higher levels in the former. PCT is a novel biomarker for diagnosing infectious pleural effusion, and it would be worthwhile to investigate the role of pleural PCT in assessing severity of illness, risk stratification, and antibiotic stewardship in hospitalized patients with pleural effusions. Journal of Hospital Medicine 2016;11:363-365. 2016 Society of Hospital Medicine.