Diagnostic value of adenosine deaminase activity in pericardial fluids

Background. The activity of adenosine deaminase (ADA) was determined in ser um and pericardial fluid of 70 patients (ages 21 to 71 years) with pericard ial effusions of various etiologies and in 15 control subjects. Methods. The patients were subdivided into five groups on the basis of defi nite diagnosis: 1) 24 patients with tuberculosis; 2) 22 with malignancies; 3) 12 with uremic pericarditis; 4) 12 with purulent pericarditis; 5) 15 con trol individuals without pericardial disease. The activity of ADA was deter mined at the same time in serum and cell-free pericardial fluid according t o the method of Karker with minor modification. Results. Mean (+/-SD) ADA activity in pericardial fluid was 66.92+/-4.12 IU /L in group 1; 27.50+/-6.02 in group 2; 28.65+/-4.73 in group 3; 53.05+/-11 .14 in group 4; and 5.67+/-1.99 in group 5, Comparing the level achieved in group 1 with all others, the difference is significant at the p<0.001 leve l. When the cut-off value of 50 IU/L is used the sensitivity of the test fo r diagnosis of tuberculous effusion is 1, and the specificity is 0.83. Stat istical analysis showed that there was no correlation between serum ADA act ivity and ADA activity in pericardial fluid, Conclusions. We recommend that determinations of ADA activity in pathologic pericardial fluids seem to be of great value in the early diagnosis of tub erculous pericardial effusions, Levels above 50 IU/L in effusions indicate probable tuberculosis.