A 27-year-old man has right-sided pleuritic pain and evening fever for 3 weeks. Pleural tap yields straw-colored fluid: protein 4.6 g/dL, LDH 420 IU/L, glucose 58 mg/dL, pH 7.38, WBC 2,400/uL with 85% lymphocytes. Sputum AFB smears are negative twice. Adenosine deaminase is 58 U/L (upper limit of normal 40 U/L). Most likely diagnosis?

• A Complicated parapneumonic effusion
• B Tuberculous pleural effusion ✓
• C Rheumatoid pleuritis
• D Malignant pleural effusion

Explanation

Tuberculous pleuritis is typically a lymphocyte-predominant exudate with a markedly elevated adenosine deaminase above 40 U/L in a young patient from an endemic setting; smears are negative because the effusion is paucibacillary and hypersensitivity driven. Complicated parapneumonic effusions show neutrophil dominance with low pH and low glucose, and rheumatoid pleuritis classically gives glucose below 30 mg/dL with a very low pH, neither of which fits this fluid.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.