Diagnostic value of interferon-gamma assay in tuberculosis pericardial effusions: study on a cohort of Iranian patients.

Tuberculosis pericarditis as a potentially fatal complication of tuberculosis requires effective diagnosis and treatment. We evaluated the efficacy of interferon-gamma (IFN-gamma) and adenosine deaminase (ADA) for diagnosing tuberculosis pericarditis in a cohort of Iranian patients presenting with pericarditis. We enrolled 38 patients with presentation of pericarditis. All patients underwent diagnostic and therapeutic pericardiostomy with drainage and biopsy. Adenosine deaminase and interferon-gamma levels were determined in pericardial fluid samples of all patients. Pericardial tissue samples were submitted for histopathologic and microbiologic studies. Polymerase chain reaction (PCR) was performed on all pericardial fluid samples to detect Mycobacterium tuberculosis. From 38 patients with pericarditis, 7 cases were diagnosed as having tuberculosis pericarditis (18.4%). Mean concentration of interferon-gamma in tuberculosis group was significantly higher compared to non-tuberculosis group (69257 pg/l [range: 26600-148000] vs. 329 pg/l [range: 0-2200], P<0.000). Receiver operating characteristic (ROC) curve showed a value of 14400 pg/l as the cutoff point with a sensitivity of 100% and specificity of 100% for diagnosing tuberculosis pericardial effusion. Adenosine deaminase was not found to be significantly higher in tuberculosis group in comparison with non-tuberculosis causes of pericardial effusion (35.7 [range: 9-69] vs. 36.03 [range: 8-420], P=0.28). In this study interferon-gamma showed to be a valuable diagnostic test for detection of tuberculosis pericarditis among a cohort of Iranian patients. We suggest using interferon-gamma to diagnose tuberculosis pericarditis to make diagnose in case of suspicion. While in this study, adenosine deaminase measurement did not prove to have the characteristics of an accurate diagnostic test for tuberculosis pericarditis.