A 48-year-old woman is found to have a unilateral pleural effusion. Thoracentesis shows: protein 4.8 g/dL, serum protein 7.2 g/dL, LDH 380 IU/L, serum LDH 210 IU/L, glucose 28 mg/dL, pH 7.10. Which is the most likely diagnosis and necessary immediate action?
- A Malignant effusion; repeat cytology and consider pleurodesis
- B Tuberculous pleuritis; RNTCP category I ATT for 6 months
- C Complicated parapneumonic effusion or empyema; prompt chest drain insertion ✓
- D Rheumatoid pleuritis; oral prednisolone without drainage
Explanation
The effusion is exudative (Light's criteria: pleural/serum protein ratio 4.8/7.2 = 0.67 >0.5; pleural/serum LDH ratio 380/210 = 1.81 >0.6). Low pH (<7.2) and low glucose (<60 mg/dL) indicate a complicated parapneumonic effusion or frank empyema requiring tube thoracostomy for drainage plus antibiotics. In malignant effusion, glucose and pH may be low but the clinical and microbiological context plus cytology differentiate it. Rheumatoid pleuritis characteristically shows glucose <30 mg/dL but requires drainage if symptomatic; the low pH here mandates urgent drainage regardless.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.