Disorders of the Pleura |

Factors Affecting Pleural Adenosine Deaminase Level in Tuberculous Pleural Effusion FREE TO VIEW

Tunn Ren Tay*, MMed; Kim Huat Tee, MMed
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Changi General Hospital, Singapore, Singapore

Chest. 2012;142(4_MeetingAbstracts):493A. doi:10.1378/chest.1384641
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SESSION TYPE: Pleural Biomarkers

PRESENTED ON: Monday, October 22, 2012 at 04:00 PM - 05:30 PM

PURPOSE: Adenosine deaminase (ADA) is an enzyme required for differentiation of lymphoid cells and monocytes. It is useful in diagnosing tuberculous (TB) pleural effusion. Previous studies using ADA level of 50 U/L have shown high sensitivity and specificity in lymphocytic effusions. However there remains a subgroup of patients with pleural TB but low ADA. This study aims to identify patient and pleural fluid characteristics affecting pleural ADA level in TB pleural effusion so as to better characterise this group of patients.

METHODS: Retrospective study of all patients admitted from Jan 2007 to Oct 2011 to a teaching hospital in Singapore with pleural TB confirmed microbiologically or histologically. Patients were divided into low ADA group (≤ 50 U/L) and high ADA group (>50 U/L). Clinical data obtained included demographic characteristics, pleural fluid analyses and differential blood counts. Univariate analyses were performed using Student’s t test and Chi Square test. Multivariate analysis was performed using logistic regression.

RESULTS: 80 patients were studied of which 7 had ADA ≤ 50 U/L (8.75%). Patients in the low ADA group were older (age 62.4±25.5 vs 42.4±17, p=0.006), had lower pleural protein (35.5±14.8 vs 50.4±6.8 g/L, p=0.035), lower pleural cell count (365±162 vs 2125±1909, p<0.001) and lower absolute pleural lymphocyte count (243±151 vs 1724±1630, p<0.001). However these factors were not found to be significant in multivariate analysis. There was no difference between the 2 groups in terms of gender, race, pleural fluid LDH and blood count, or any correlation between ADA level and subsequent pleural fluid and biopsy culture or histology positivity.

CONCLUSIONS: Patients with pleural TB and low ADA were older, had low pleural protein, cell count and absolute lymphocyte count

CLINICAL IMPLICATIONS: For older patients and those with low pleural protein and cell count, a low pleural fluid ADA does not exclude TB. More extensive tests should be done to confirm or exclude pleural TB in these patients.

DISCLOSURE: The following authors have nothing to disclose: Tunn Ren Tay, Kim Huat Tee

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Changi General Hospital, Singapore, Singapore




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