Diagnostic Value of high sensitivity C-reactive protein in Differentiating Transudate and Exudative Fluid in Patients with Pleural Effusion.

Pleural effusion is the accumulation of fluid in the pleural cavities resulting from an imbalance of fluid production and reabsorption. Early detection of the cause of pleural effusion leads to early treatment and reduces effects on the patient. The most important step in pleural effusion diagnosis is to determine its nature and to determine whether it is transudate or exudate. CRP(C-reactive protein) is an acute-phase protein that is synthesized by hepatocytes during inflammatory states, the highly sensitive type of CRP is more sensitive than the standard CRP test and measures lower levels. It may help differentiate the nature of pleural effusion. The aim of this research was to evaluate the hs-CRP diagnostic value in differentiating the nature of the pleural effusion

In this descriptive-analytical cross-sectional study, in Rohani hospital of Babol from March 2017 to February 2019, 75 pleural effusion patients, undergoing thoracentesis, the hs-CRP level was measured in their pleural fluid and were compared based on Light´s criteria in two groups of transudates and exudates. Using the ROC curve, the appropriate cut-off point was determined for hs-CRP to differentiate the nature of pleural effusion.

Out of 75 patients, 45 patients were in the exudative pleural effusion group and 30 patients in the transudative group. The mean of hs-CRP in the exudate group was 18.27±10.74 mg/L and in the transudative group 2.98±2.15 mg/L (p˂0.001). The cut-off point for hs-CRP of pleural fluid was calculated to be 5.94 mg / L, which has a sensitivity of 88.9% and a specificity of 93.3%. This marker was also studied in exudative subgroups, and there was a significant difference between pleural hs-CRP levels in two groups of pleural effusion due to malignancy and Parapneumonic effusion (p=0.011).

The pleural fluid hs-CRP can be used as a useful marker for differentiating the nature of pleural effusion and differentiating the pleural effusion of transudate and exudate.