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Traditional diagnostic tests for pericardial tuberculosis (TB) are insensitive and often require long culture periods, and this has led to more emphasis being placed on biochemical tests such as the pericardial adenosine deaminase (ADA) test. However, controversy exists as to its diagnostic utility. In addition, the use of interferon (IFN)-gamma, which is a reliable indicator of pleural and peritoneal TB, has not been explored in pericardial effusions. We investigated ADA and IFN-gamma levels in pericardial effusions of different etiologies.A prospective study was carried out from February 1995 to February 1998 at Tygerberg Hospital (South Africa), with pericardial taps being performed under echocardiographic guidance. During this period, 110 consecutive patients presenting with large pericardial effusions were included in the study. Diagnoses were made according to predetermined criteria, and they included TB (n = 64), malignancy (n = 12), nontuberculous infections (n = 5), other effusions (n = 19), and effusions of uncertain origin (n = 10). The median ADA level in the tuberculous group was 71.7 U/L (range, 10.3 to 303.6 U/L), which was significantly higher than that in any other group (p0.05). With a cutoff level for ADA activity of 30 U/L, sensitivity was 94%, specificity was 68%, and positive predictive value was 80%. IFN-gamma levels were determined in 30 subjects. The median IFN-gamma concentration in the tuberculous group was1,000 pg/L, which was significantly higher than in any other diagnostic group (p0.0005). A cutoff value of 200 pg/L for IFN-gamma resulted in a sensitivity and specificity of 100% for the diagnosis of pericardial TB.Pericardial fluid levels of ADA and IFN-gamma are useful in the diagnosis of tuberculous pericarditis.

Study objectives: To determine the biochemical characteristics of large pericardial effusions in various disease states, and to assess their utility as diagnostic tools. Setting: An academic university hospital in the Western Cape, South Africa. Design: Consecutive, prospective case series. Patients: One hundred ten hospital patients > 12 years old, who presented to the echocardiography department with large pericardial effusions, and 12 control subjects who underwent open-heart surgery (coronary artery bypass graft or aortic valve replacement). Measurements: Fluid was sent for examination of biochemistry, adenosine deaminase, microbiology, hematology, and cytology. The etiology of each pericardial fluid sample was established using predetermined criteria. Results: The biochemistry of pericardial exudates differed significantly from pericardial transudates. Light’s criteria (whereby an exudate is defined as having one or more of the following: pleural fluid/serum protein ratio > 0.5; pleural fluid/serum lactate dehydrogenase [LDH] ratio > 0.6; and/or pleural fluid LDH level > 200 U/L) were applied to pericardial fluids and demonstrated to be the most reliable diagnostic tool for identifying pericardial exudates. The corresponding sensitivity was 98%. Conclusion: Although laboratory tests are a useful guideline when assessing the etiology and pathophysiology of pericardial effusions, the majority of large, clinically significant pericardial effusions result from exudative causes. (CHEST 2002; 121:495– 499)