Additional pleural fluid studies

(NEJM 2002;346:1971)

NT-proBNP ≥1500 pg/mL

has 91% Se & 93% Sp for CHF (Am J Med 2004;116:417)

WBC & diff.:

exudates tend to have ↑ WBC vs. transudates but nonspecific neutrophils → parapneumonic, PE, pancreatitis lymphocytes (>50%) → cancer, TB, rheumatologic eos (>10%) → blood, air, drug reaction, asbestos, paragonimiasis, Churg-Strauss, PE

RBC:

Hcteff 1–20% → cancer, PE, trauma; Hcteff/Hctblood >50% → hemothorax

acid-fast bacilli

yield in TB 0–10% with stain, 11–50% with culture, ~70% with pleural bx adenosine deaminase (ADA): seen with granulomas, >70 suggests TB, <40 excludes TB

cytology:

ideally ≥150 mL and at least 60 mL should be obtained (Chest 2010;137:68)

glucose:

<60 mg/dL → malignancy, infection, RA

amylase

seen in pancreatic disease and esophageal rupture (salivary amylase) rheumatoid factor, CH50, ANA: limited utility in dx collagen vascular disease

triglycerides:

110 → chylothorax, 50–110 → ✓ lipoprotein analysis for chylomicrons

cholesterol:

60; seen in chronic effusions (eg, CHF, RA, old TB)

creatinine:

effusion/serum ratio >1 → urinothorax fibulin-3: ↑ plasma and/or effusion levels → mesothelioma (NEJM 2012;367:1417)