Abstract / Summary
Background: Alkaline phosphatase (ALP) has been used as a marker in pleural fluid to determine the cause of pleural effusions with varied results. Our study aimed to evaluate the role of pleural fluid ALP (P ALP) and pleural fluid to serum ALP (P/S ALP) ratio in differentiating transudative and exudative pleural effusions and tubercular from other exudative effusions. Materials and Methods: It was a diagnostic study including all consecutive patients with a diagnosis of pleural effusion. Aspiration of pleural fluid was performed in these cases and the sample was sent for the estimation of ALP level along with other required tests. Receiver operating characteristic (ROC) curves and areas under the curves (AUC) with 95% confidence intervals were used to determine the optimum cutoff points. Results: We included a total of 115 patients were included in the study with 97 (84.3%) exudative effusions and 18 (15.7%) transudative effusions. A cutoff value of 17 IU/L was reported with a sensitivity of 94.9% and specificity of 83.3% to differentiate transudative and exudative effusions. A cutoff value of 0.29 for P/S ALP ratio was recommended to differentiate the two conditions with a sensitivity of 77.5% and specificity of 94.4%. P ALP and P/S ALP ratio had no significant role in differentiating tubercular from other exudative effusions. Conclusion: P ALP and P/S ALP ratio can be used to differentiate transudates from exudates and tubercular from transudative effusions. It, however, cannot differentiate tuberculosis from other exudative effusions.