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posted Aug 19, 2014, 8:54 AM by Kevin Hauck   [ updated Aug 19, 2014, 8:57 AM ]

A new post by for Resident-As-Teacher Carly Glick.

Pleural Effusions

Last week’s CRS at Moses was about a young previously healthy male presenting with cough x 6 weeks, L sided chest pain x 4 days, DOE, and weight loss. The physical exam and CXR showed unilateral pleural effusion. Thoracentesis had lymphocytic predominance consistent with TB. This Monte Minute will focus on reviewing pleural effusions.


Pleural Effusion

  • Definition—excess quantity of fluid in pleural space
  • Etiology—pleural fluid formation exceeds pleural fluid absorption
  • Symptoms (if not asymptomatic)—dyspnea, dry cough, chest pain, orthopnea
  • Physical exam


Sensitivity (%)

Specificity (%)

LR if present

LR if absent

Probability of having effusion

Asymmetic chest expansion





If asymmetric expansion is present, 40% inc prob. If absent, 30% dec prob.

Decreased tactile fremitus





If present, 32% inc prob. If absent, 30% dec prob

Dullness to percussion





If present, 30% inc prob. If absent, 45% dec prob.

Diminished/absent breath sounds





If present, 30% inc prob. If absent, 45% dec prob.

Diminished resonance





If present, 35% inc prob. If absent, 30% dec prob.



Analysis of pleural fluid

  • Light’s Criteria—exudative if one of following is fulfilled
    • Pleural fluid protein/serum protein ratio >0.5
    • Pleural fluid LDH/serum LDH ratio >0.6
    • Pleural fluid LDH > 2/3 upper limits of the lab’s normal serum LDH
  • Types
    • Transudates—secondary to imbalances in hydrostatic and oncotic pressures in chest
      • CHF (will be bilateral in 90% with LV failure), renal failure, cirrhosis
    • Exudates
      • Infection, malignancy, hemothorax (trauma, PE, metastatic disease), chylothorax (mediastinal tumor) inflammation, immunologic responses
  • Chemical analysis to help narrow differential
    • Protein
      • Mostly <3 g/dL in transudates
      • >4 g/dL in TB pleural effusions
      • >7-8 g/dL in Waldenstrom’s macroglobulinemia and multiple myeloma
    • LDH
      • >1000 IU/L in empyema, rheumatoid pleurisy, pleural paragnimiasis
      • Pleural fluid/serum LDH ratio>1 and pleural fluid/serum protein ratio <0.5 in PCP
    • Triglycerides
      • >110 in chylothorax
    • Glucose
      • <60 mg/DL or pleural fluid/serum glucose ratio >0.5 found in rheumatoid pleurisy, complicated parapneumonic effusion, empyema, malignancy, TB pleurisy, lupus pleuritis, esophageal rupture
    • pH
      • <7.30 in empyema, malignancy, TB pleurisy, rheumatoid pleurisy
    • Amylase
      • If pleural fluid amylase > upper limits of normal for serum amylase then differential narrowed to acute pancreatitis, chronic pancreatic pleural effusion, esophageal rupture, malignancy
    • White cells
      • Nucleated cells
        • >50000àComplicated parapneumonic effusions, empyemas
        • >10000àbacterial pneumonia, acute pancreatitis, lupus pleuritis
        • <5000àTB pleurisy, malignancy
      • LymphocytosisàTB pleurisy, lymphoma, sarcoidosis, chronic rheumatoid pleurisy, chylothorax, carcinomatous
      • Eosinophiliaàpneumothorax, hemothorax, pulmonary infarction, parasitic disease, fungal infection, malignancy, drugs


And now back to our patient…


TB pleural effusions

·       Pathogenesis—delayed hypersensitivity reaction to mycobacteria and mycobacterial antigens in the pleural space

o   Organisms and antigens enter the pleural space from leakage or rupture

o   Can become chronic and progress into an empyema

·       Clinical manifestations

o   Represents reactivation disease (usually in adults) or primary TB (usually in children)

o   Usually unilateral

o   Present with acute febrile illness with nonproductive cough, pleuritic chest pain

§  Sometimes presents with night sweat, chills, weakness, dyspnea, weight loss

·       Radiographic imaging

o   Unilateral, R sided 55% of time

o   Usually occupy <1/3 of hemithorax

·       Diagnosis

o   Pleural fluid—straw colored, exudative, protein >3.0 g/dL, LDH >500 IU/L, pH<7.40, glucose=60-100 mg/DL, lymphocyte-predominant

§  Cultures are positive in 12-80% patients

§  Can test pleural fluid adenosine deaminase (ADA) level

o   If pleural fluid is nondiagnositic, pleural biopsy is indicated if TB pleurisy is suspected

o   Sputum culture positive in 20-50% of patients

·       Treatment is same as pulmonary TB




Harrison’s Principles of Internal Medicine

Evidence-Based Physical Diagnosis