The Value of Measurment of Bilirubin in Pleural Fluid in the Differentiation between Exudative and Transudative Pleual Effusion
Keywords:Bilirubin; Pleural fluid; exudative; Transudative pleural effusion
Background: The pleural effusion is a common clinical problem which can be exudative or transudative
in nature due to variety of causes. Measurement of biochemical markers in the pleural fluid is an important
measure to distinguish exudative from transudative effusion.
Aim of the Study: Is to determine the value of pleural fluid to serum bilirubin ratio to differentiate between
transudative and exudative pleural effusion.
Patients and Method: Thirty-five patients enrolled in this study, they admitted to medical ward in Baghdad
teaching hospital and submitted to clinical, radiological, ultrasonographic examination proved to have
pleural effusion from December 2018 to July 2019. Samples of blood and pleural fluid aspirated in the
medical ward, analyzedafter 30-60 minute of aspiration. The sample of some cases were analyzed in private
laboratories. Serum protein, total serum bilirubin and other investigation according to the condition of the
patient like blood urea, serum creatinine, liver function test, sputum of AFB. Pleural fluid analyzed from
protein, total bilirubin, cell count, differential and cytology .Pleural biopsy was done to patients suspected
to have malignant or tuberculous effusion and grouped at the end of their hospitalization into exudative
and transudative effusion according to specific etiology, clinical examination, radiological finding, and
then measure the pleural fluid to serum protein ratio, pleural fluid to serum bilirubin for each patient. We
depended on pleural fluid to serum protein ratio to compare with pleural fluid to serum bilirubin ratio for
differentiation between exudative and transudative pleural fluid.
Results: Twenty two patients with exudative effusion and thirteen patients were having transudate according
to pleural fluid to serum protein (Light ’s criteria). P-value= 0.002, Fisher. Exact test= 0.001. Twenty three
patients with exudative effusion and twelve patients with transudative effusion according to pleural fluid
to serum bilirubin ratio. P value= 0.37, Fisher. Exact test = 0.45. Pf/s ratio can increase the sensitivity and
specificity of Light ‘s criteria.
Conclusions: Pleural fluid to serum bilirubin ratio can’t replace Light’s criteria in differentiation between
exudates and transudate pleural effusion. Pf/s bilirubin ratio is a reliable test can easily perform but not
common use in our hospital because of its costy and not familial use in our laboratories.
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