Pleural Fluid and Serum Leptin Levels in the Differential Diagnosis of Pleurisy

Objective: To investigate the diagnostic value of serum and pleural fluid leptin levels in the differentiation between transudate and exudate, tuberculosis and nontuberculosis pleural effusion, and different diseases in treatment-naïve patient groups with different diseases that present with pleural fluid (pleural fluid due to tuberculosis, malignant pleural fluid, transudative pleural fluid and parepneumonic pleural fluid).
Methods: The study comprised a total of 78 consecutive cases (32 females and 46 males). The cases were assigned to two groups as transudative and exudative pleural effusion according to Light criteria. Cases with exudative fluid were divided into three groups; tuberculosis (TB), nonspecific (parapneumonic) and malignant pleural fluid. Weight and height were measured in all patients and body mass index (BMI) was calculated. Pleural fluid and serum leptin levels were measured in all disease groups and their diagnostic value was investigated.
Results: Leptin levels were measured in the serum and pleural fluids and adenosine deaminase (ADA) level was studied in the pleural fluids of the patients. No statistically significant difference was determined between leptin levels of patients that were grouped according to their diagnosis (p<0.05). There was also no significant difference between transudate and exudates in terms of leptin and ADA levels. When the patients were grouped as TB and non-TB, no difference was found between the groups in terms of serum and pleural fluid leptin levels, whereas pleural ADA concentration was significantly higher in the tuberculosis group in comparison to the other group. A weak positive correlation was determined between body mass index and serum and pleural leptin levels (r=0.39 and r=0.42 respectively, p<0.001).
Conclusion: Nevertheless the present study included a limited number of patients, serum and pleural leptin levels remained inadequate both in the differentiation between transudates and exudates and in achieving an etiological diagnosis. Despite the results suggesting a significant decrement in tuberculosis pleurisy, it is clear that further studies are needed on this subject.