Alkaline phosphatase in pleural effusions.

BACKGROUND Pleural effusion (PF) is a common clinical presentation in several diseases. Various parameters from pleural fluid have been studied to identify the cause. The diagnostic value of these parameters varies. The present study was carried out to evaluate the value of alkaline phosphatase concentration in the pleural effusions as a diagnostic tool. METHODS One hundred and one patients with pleural effusion admitted over a period of two years were studied. The diagnosis was confirmed by pleural biopsy and cytology for malignant cells. RESULTS Pleural fluid alkaline phosphatase levels of more than 75 mg/dl was found in exudative effusions and less than 75 mg/dl in transudative ones. But it did not differentiate tubercular pleural effusions from other exudative ones. CONCLUSION Pleural fluid alkaline phosphatase of >75 mg/dl is a useful biochemical marker to suggest exudative effusions.