Clinical Utility of Red Cell Distribution Width in Patients with Pleural Effusion

The red cell distribution width (RDW) value has been recently recognized as a valuable biomarker in clinical practice. The RDW value has not been evaluated so far in patients with pleural effusion. Thus, this study aimed to investigate whether RDW could distinguish between exudative and transudative pleural effusions.

We measured protein and lactate dehydrogenase levels on both pleural fluids and serum samples from 223 cases and classified them as transudates or exudates based on the classic Light's criteria. We collected blood cell count elements such as RDW from the medical records. We also investigated the correlation between RDW and the nature of pleural effusion.

In 55.2% of the patients, pleural fluid was exudative. Although we found no significant association between RDW and the nature of the pleural fluid, we detected a significantly higher amount of RDW (14.9 ≤) in patients with exudative pleural effusion compared to transudate (66.7% vs. 33.3%; P= 0.01). In this category, neoplastic conditions were mostly observed in the patients (76.3%), followed by pulmonary thromboembolism (21.1%) and systemic lupus erythematous (2.6%).

The findings could not reveal any noticeable correlation between RDW and the Light criteria. However, it appears that elevated RDW levels give insights into the valuable nature of RDW in different conditions such as neoplastic diseases.