ABSTRACT

To evaluate the diagnostic performance of adenosine deaminase (ADA) levels in patients with exudative lymphocytic pleurisy for the differential diagnosis of tuberculous pleurisy (TBP) and malignant pleural effusion (MPE).

Data on patients with exudative lymphocytic pleurisy were retrospectively analyzed. The study population comprised 54 patients. Thirtyseven were diagnosed with TBP and 17 were diagnosed with MPE.

Significant differences were determined in terms of age and ADA, total protein, albumin, and LDH levels between the TBP and MPE groups. The optimal cut-off value of ADA levels was 35.1 U/L for diagnosing TBP. Sensitivity and specificity were 92% and 100%, respectively. Logistic regression analysis was performed to assess independent variables associated with TBP. Independent predictive factors in the model were ADA (OR: 1.21, 95% CI: 1.06–1.39, p=0.006)], and (OR: 0.92, 95% CI: 0.84–1.00, p = 0.052)]. The AUC value by the regression equation was 0.979 (p<0.001). When patients were categorized according to age (<50 ve ≥50), two different cut-off values (>13.51 and >35.1) for each age range were found in all, but one, TBP patients.

ADA levels are useful for the diagnosis of TBP in cases where pleural biopsy cannot be performed or that are inconclusive in making a diagnosis of TBP. In this group, reducing the conventional cut-off value and/or performing an age-based approach seems to improve the diagnostic performance of ADA levels.

Keywords: Adenosine deaminase, malignancy, tuberculosis, pleurisy