A pleural fluid analysis shows: protein 52 g/L (serum 65 g/L), LDH 450 IU/L (serum LDH 250 IU/L), glucose 1.5 mmol/L (serum 5.4 mmol/L), pH 7.05, and pleural fluid WBC 25,000/mm³ predominantly neutrophils. By Light's criteria, this is an exudate. The pH and glucose strongly suggest:
- A Uncomplicated parapneumonic effusion
- B Complicated parapneumonic effusion or empyema requiring drainage ✓
- C Malignant pleural effusion
- D Rheumatoid pleuritis
Explanation
In parapneumonic effusions, Light's criteria guide management: pH <7.2, glucose <2.2 mmol/L, and LDH >3× ULN are criteria for complicated parapneumonic effusion requiring drainage (intercostal tube drainage or VATS). A pH below 7.0 indicates empyema. This effusion has pH 7.05 and glucose 1.5 mmol/L — these are classic indicators of complicated parapneumonic effusion/early empyema requiring immediate chest tube drainage. Simple parapneumonic effusions respond to antibiotics alone. Malignant effusions rarely have pH <7.2 unless there is concurrent infection. Rheumatoid pleuritis can have low pH/glucose but typically in chronic effusions.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.