Use of pleural fluid C-reactive protein in diagnosis of pleural effusions

Abstract

ABSTRACT

BACKGROUND :Pleural  effusion is commonly  manifested in pulmonary ,pleural or extra-pulmonary disease .It may be transudate ,caused  by heart failure or exudate,  induced by  inflammation, infection,  or neoplasm .Despite the progress  made on its investigation methods , it is still a major diagnostic problem.A specific test is therefore required for differential diagnosis of pleural effusion.C-reactive protein is an acute phase protein synthesized by hepatocytes.Few studies had reported the value of pleural C-reactive protein in differentiating between transudative and exudative effusions ,and in the aetiological diagnosis of exudative pleural effusion as well.

OBJECTIVE: The purpose of this study is to: Evaluate the role of pleural fluid CRP in discriminating between transudative and exudative effusions . Determine the value of pleural CRP in the aetiological diagnosis of exudative pleural effusion.

Materials and Methods: A cross-sectional  study at ALmoasat university hospital between March 2018 and March 2019.

Pleural fluid CRP levels were obtained in 62 patients with pleural effusion, using an immunoturbidmetric method. According to the criteria used 20 patients included in the transudate group and 42 patients in the exudate group. In the exudate group 10 patients had parapneumonic effusion, 18  neoplastic effusions, 9 tuberculous effusion, and 5 pulmonary embolism. We compared first CRP levels between transudates and exudates. Then between the  causes of exudative effusion.

RESULS: Pleural fluid CRP levels were significantly higher in the exudate group(P=0.000). When the exudate  sub-groups were compared, the parapneumonic  effusion CRP levels were significantly higher than those in non-parapneumonic  effusions (tuberculous, neoplastic, pulmonary embolism)(P=0.000). The tuberculous effusion CRP levels were lower than those in  parapneumonic effusions but they are significantly higher than those found in malignant effusion subgroup(P=0.03).

CONCLUSION: Pleural CRP tittering could be a useful diagnostic marker for differentiation between exudative and transudative pleural effusions. In the differential diagnosis of plueral effusions, higher CRP levels may prove to be a rapid, practical and accurate test of differentiating infective effusions (parapneumonic or tuberculous) from other exudate types. Pleural fluid CRP ≥14 mg/l had 74% sensitivity and 90% specificity in diagnosis of exudate. Pleural fluid levels ≥79 mg/l had 50% sensitivity and 100% specificity in diagnosis of parapneumonic effusion. Pleural fluid levels ≥42.5mg/l had 68.4%sensitivity and 100% specificity in diagnosis of infective effusion. Pleural CRP>42.5mg /l exclude totally malignant effusion..