Tuberculous pleural effusion is characterized by all except?
**Core Concept**
Tuberculous pleural effusion is a type of exudative pleural effusion characterized by the accumulation of fluid in the pleural space due to tuberculosis infection. This condition is often associated with a chronic inflammatory response, leading to the production of specific cytokines and chemokines that promote fluid accumulation.
**Why the Correct Answer is Right**
Tuberculous pleural effusion is typically characterized by a lymphocytic predominance, with a high percentage of lymphocytes in the pleural fluid, often exceeding 80%. This is due to the chronic inflammatory response to Mycobacterium tuberculosis, which triggers the activation of T lymphocytes and the production of cytokines such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). The pleural fluid also typically has a high adenosine deaminase (ADA) level, which is a marker of cellular immunity.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because tuberculous pleural effusion is not typically characterized by a high glucose level in the pleural fluid. In fact, the glucose level is often low, which is a distinguishing feature from other types of exudative pleural effusions.
**Option B:** This option is incorrect because tuberculous pleural effusion can be associated with a high lactate dehydrogenase (LDH) level in the pleural fluid, which is a marker of cellular damage.
**Option C:** This option is incorrect because tuberculous pleural effusion is not typically characterized by a high pH level in the pleural fluid. In fact, the pH is often low, which is a distinguishing feature from other types of exudative pleural effusions.
**Clinical Pearl / High-Yield Fact**
A high adenosine deaminase (ADA) level in the pleural fluid is a useful diagnostic clue for tuberculous pleural effusion, with a sensitivity of around 80%. This is because ADA is a marker of cellular immunity, and the high levels of ADA in the pleural fluid reflect the chronic inflammatory response to Mycobacterium tuberculosis.
**Correct Answer:** A.