Objective: To determine if telomerase activity can differentiate malignant from tuberculous pleural effusions.
Design: Telomerase activity in malignant and tuberculous pleural effusions was measured in a blinded manner using a PCR-based telomeric repeat amplification protocol (TRAP) assay.
Material and Method: Fifty-two patients with lymphocytic exudative pleural effusions were identified on thoracocentasis over a period of 18 months
Results: Telomerase activity was detected in 34% of malignant pleural fluid samples and 50% of tuberculous pleural effusions. The positive rate of telomerase activity was 30.7% for primary lung cancer and 37.5% for metastatic pleural effusion. The sensitivity and specificity of telomerase activity assay were extremely low (35.7% and 52.9%, respectively), compared with that of cytological examination (52.6% and 65.4%, respectively). Moreover, the diagnostic accuracy of telomerase activity in combination with cytology was even lower than cytological examination alone (46.7% vs. 60%, respectively). This finding was in contrast to previous reports and demonstrated that the detection rate of telomerase activity in tuberculous pleural effusions was greater than that observed in malignant pleural exudates.
Conclusion: Telomerase activity does not appear to be a useful marker for differentiating malignant from tuberculous effusions

Keywords: Telomerase activity, Malignancy, Tuberculosis, Pleural effusion