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Poor diagnostic value of adenosine deaminase in pleural, peritoneal & cerebrospinal fluids in tuberculosis
Abstract:
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.
Insights
Adenosine deaminase (ADA) levels in bodily fluids show limited diagnostic value for tuberculosis. While some values were statistically significant, the wide scatter makes ADA testing unreliable for routine tuberculosis diagnosis.
Area of Science:
- Clinical diagnostics
- Infectious diseases
- Biochemistry
Background:
- Tuberculosis (TB) diagnosis can be challenging, especially in extrapulmonary forms.
- Adenosine deaminase (ADA) is an enzyme that may be elevated in TB.
- Investigating the utility of ADA as a diagnostic marker is crucial for improving TB detection.
Purpose of the Study:
- To evaluate the diagnostic usefulness of adenosine deaminase (ADA) estimation in pleural, peritoneal, and cerebrospinal fluids for tuberculosis.
- To determine the sensitivity, specificity, and predictive values of ADA levels in various body fluids for TB diagnosis.
Main Methods:
- Adenosine deaminase (ADA) levels were measured in 84 pleural, 140 peritoneal, and 136 cerebrospinal fluid samples.
- Diagnostic performance metrics (sensitivity, specificity, PPV, NPV) were calculated for TB diagnosis using established ADA cut-off values for each fluid type.
- ADA levels were also assessed in plasma, lymphocytes, and cell fractions.
Main Results:
- Pleural fluid ADA showed moderate sensitivity (67%) and high specificity (92%) for TB (cut-off > 30 U/L).
- Peritoneal fluid ADA had high sensitivity (89%) but lower specificity (81%) (cut-off > 15 U/L), with a very low positive predictive value (25%).
- Cerebrospinal fluid ADA demonstrated low sensitivity (50%) but high specificity (90%) (cut-off > 10 U/L).
- Significant differences in mean ADA levels between tuberculous and non-tuberculous fluids were observed, but with considerable overlap and scatter, limiting clinical utility.
- ADA estimation in plasma and cellular components did not provide additional diagnostic value.
Conclusions:
- Adenosine deaminase (ADA) estimation has limitations as a routine diagnostic test for tuberculosis in pleural, peritoneal, and cerebrospinal fluids due to variable sensitivity, specificity, and predictive values.
- The wide scatter of ADA values in both tuberculous and non-tuberculous samples reduces its practical clinical value, particularly for peritoneal and cerebrospinal fluids.
- Further research into more reliable biomarkers for tuberculosis diagnosis is warranted.