American Association of Critical-Care Nurses (AACN) Certification Practice Test

What does a serum glucose level equal to pleural fluid glucose suggest?

1. Exudative effusion

2. Transudative effusion

3. Chylous effusion

4. Hemothorax

The correct answer is: Transudative effusion

A serum glucose level that equals the pleural fluid glucose level typically suggests that the pleural effusion is transudative. Transudative effusions occur when there is an imbalance in hydrostatic and oncotic pressures, often seen in conditions like heart failure or cirrhosis. In these cases, the pleural fluid composition is more similar to serum due to systemic factors affecting fluid movement, thereby leading to equivalent glucose levels. In contrast, exudative effusions are usually associated with more complex pathologies, such as infections or malignancies, where the pleural fluid glucose would often be lower than serum glucose due to consumption by cells (like bacteria or cancer cells) or inflammatory processes. Chylous effusions contain lymphatic fluid with high triglyceride levels, typically unrelated to glucose levels. Hemothorax involves blood accumulation in the pleural cavity, where glucose levels may not give the same indicative information about serum comparisons as they do in transudative or exudative processes.