Poor diagnostic value of adenosine deaminase in pleural, peritoneal & cerebrospinal fluids in tuberculosis.

Adenosine deaminase (ADA) was estimated in 84 pleural, 140 peritoneal and 136 cerebrospinal fluids to study its diagnostic usefulness as a routine test for tuberculosis. The sensitivity, specificity, positive and negative predictive values for diagnosing tuberculosis in pleural fluids (ADA > 30 U/l) was 67, 92, 78 and 87 per cent respectively, in peritoneal fluids (ADA > 15 U/1) it was 89, 81, 25 and 99 per cent respectively and in cerebrospinal fluids (ADA > 10 U/l) it was 50, 90 21 and 97 per cent respectively. The differences in mean ADA levels between tuberculous (28.0 and 19.5 U/1) and non-tuberculous (9.7 and 4.8 U/1) peritoneal and cerebrospinal fluids although statistically significant (P < 0.001), were of no practical clinical value. A wide scatter in ADA values was seen in both tuberculous and non-tuberculous fluids. ADA estimation in plasma, lymphocytes and cell fractions of fluids was also not diagnostically useful nor did it throw light on the source of elevated ADA in fluids.