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

What lab values are characteristic of a transudative pleural effusion?

1. Pleural fluid glucose higher than serum glucose

2. Pleural fluid pH below 7.35

3. Pleural fluid glucose equal to serum glucose, pleural fluid pH 7.40-7.55, and less than 1000 WBC/mcL

4. Pleural fluid with more than 1000 WBC/mcL

The correct answer is: Pleural fluid glucose equal to serum glucose, pleural fluid pH 7.40-7.55, and less than 1000 WBC/mcL

The characteristic lab values of a transudative pleural effusion include pleural fluid glucose that is equal to serum glucose, a pleural fluid pH ranging from 7.40 to 7.55, and a white blood cell count of less than 1000 WBC/mcL. Transudative effusions typically occur due to systemic conditions that alter hydrostatic or oncotic pressures, leading to fluid accumulation in the pleural space. As a result, the biochemical profile reflects a lower inflammatory process, resulting in a more neutral pH and a lower white blood cell count. In contrast, if pleural fluid glucose were higher than serum glucose, that would suggest a different type of pathology, typically associated with exudative processes where inflammation or malignancy might lead to changes in the pleural fluid composition. A pleural fluid pH below 7.35 usually indicates an acidic environment typically seen in complicated effusions or infections, which is not characteristic of transudative pleural effusions. Similarly, a pleural fluid white blood cell count exceeding 1000 WBC/mcL would typically indicate an exudative process or infection, further reinforcing why option C aligns with the expected lab values for transudative