Utility of amylase levels in malignant pleural effusions

BACKGROUND AND OBJECTIVE: To analyze the utility of the measurement of pleural amylase levels (AL) and pleural fluid/serum amylase ratio (AR) in malignant pleural effusions. PATIENTS AND METHOD: Prospective and comparative study of AL and its AR in relation to the patient and pleural fluid characteristics in 295 malignant effusions and 673 nonmalignant. RESULTS: There were 103 patients with AL greater than 100 U/I (11%) and 268 with AR greater than 1 (28%): 53 (18%) and 109 (37%) in malignant effusions respectively. Patients with malignant effusions had higher AL and AR, especially when tumour origin was lung cancer, had positive pleural citology or biopsy and showed an adenocarcinoma. Multivariate regression analysis revealed a significant difference in the changes in AL associated with positive pleural citology or biopsy and massive pleural effusion. The malignant effusions had higher AL in lung cancer of stage IV. CONCLUSIONS: AL and AR should not be routinely measured to exclude a malignant effusion. A high AL or AR was related to positive pleural citology or biopsy, a massive pleural effusion and lung cancer with an advanced disease.