The importance of alkaline phosphatase levels in differentiation of pleural effusions

Aim: It is known that various biochemical parameters may be used in the differential diagnoses of pleural diseases. There is a few and contradictory studies about the importance of Alkaline phosphatase (ALP) in pleural effusions. To compare ALP levels in malignant and nonmalignant effusions, transudative and exudative effusions. Material and methods: Hundred and fifteen cases with pleural effusion were included in this study. Results: Hundred had exudative, 15 had transudative pleural effusions according to Light criteria. Fourty one had malignant, 74 had benign pleural effusions. Pleural ALP and pleura/serum ALP level was significantly higher in exudative group than transudative group (p<0.05). Cut-off level for the differentiation of exudate-transudate was found to be 44.5 U/L with the sensitivity of 74% and specificity of 86%. Serum, pleural ALP and pleura/serum ALP level was not found to be significant for differentiation of malignant-benign pleural effusions. Conclusion: We found pleural fluid ALP concentration and pleura/serum ALP ratio higher in exudative group than transudative group but these values were not helpfull in differentiation of malign and benign pleural diseases.