title: Adenosine deaminase activity is a sensitive marker for the diagnosis of tuberculous pleuritis in patients with very low CD4 counts.
abstract: BACKGROUND
  Adenosine Deaminase Activity (ADA) is a commonly used marker for the diagnosis of tuberculous pleural effusion. There has been concern about its usefulness in immunocompromised patients, especially HIV positive patients with very low CD4 counts. The objective of this study was to evaluate the sensitivity of ADA in pleural fluid in patients with low CD4 counts.
  
  
  METHODS
  This was a retrospective case control study. Medical files of patients with tuberculous pleuritis and non-tuberculous pleuritis were reviewed. Clinical characteristics, CD4 cell counts in blood and biochemical markers in pleural fluid, including ADA were recorded.
  
  
  RESULTS
  One ninety seven tuberculous pleuritis and 40 non-tuberculous pleuritis patients were evaluated. Using the cut-off value of 30 U/L, the overall sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of ADA was 94%, 95%, 19, and 0.06 respectively. The mean CD4 cell counts among TB pleuritis patients was 29 and 153 cells/microL in patients with CD4 <50 cells/microL and >50 cells/microL, (p<0.05) respectively. The corresponding mean ADA values for these patients were 76 U/L and 72 U/L respectively (p>0.5). There was no correlation between ADA values and CD4 cell counts (r = -0.120, p = 0.369).
  
  
  CONCLUSIONS
  ADA analysis is a sensitive marker of tuberculous pleuritis even in HIV patients with very low CD4 counts in a high TB endemic region. The ADA assay is inexpensive, rapid, and simple to perform and is of great value for the immediate diagnosis of tuberculous pleuritis while waiting for culture result and this has a positive impact on patient outcome.
authors.affiliation: Institute of Medicine, University of Bergen, Bergen, Norway. adeola12@yahoo.co.uk
authors.forename: Kamaldeen
authors.initials: K
authors.lastname: Baba
authors.forename: Anwar A
authors.initials: AA
authors.lastname: Hoosen
authors.forename: Nina
authors.initials: N
authors.lastname: Langeland
authors.forename: Anne M
authors.initials: AM
authors.lastname: Dyrhol-Riise
mesh_terms: D000243:Adenosine Deaminase / Q000378:metabolism*; D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology*; D016022:Case-Control Studies; D005260:Female; D015658:HIV Infections / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000175:diagnosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors; D014396:Tuberculosis, Pleural / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology*
chemical_list: D015415:Biomarkers; D000243:Adenosine Deaminase