Serum adenosine deaminase activity and its isoenzyme in patients treated for tuberculosis.

OBJECTIVE

Increased serum adenosine deaminase (ADA) activity, mainly associated with tuberculosis can also occur in a number of other diseases thus negatively affecting the diagnostic utility of ADA measurements in tuberculosis. The aim of the study was to determine whether or not the combined use of the activity of ADA, its isoenzymes and differential cell counts would provide a more efficient means of diagnosing tuberculosis than the use of ADA levels alone.

DESIGN

A prospective case-control study.

PLACE AND DURATION OF STUDY

Department of Biochemistry, King Saud University, Riyadh, Kingdom of Saudi Arabia. Duration was 3 years (2000-2003).

SUBJECTS AND METHODS

Fifty healthy individuals and fifty clinically diagnosed for pulmonary tuberculosis patients were included in this study. Nine measurements of several variables including serum ADA, ADA(1), ADA(2), ratios of ADA(1)/ADA, ADA(2)/ADA, total and differential cell counts were carried out at different periods of time during 6 months of follow up.

RESULTS

Data suggested significant (p<0.05) increase in serum ADA and ADA-2 values, which decreased (p<0.05) during the first 2 months in the patients as a whole, followed by stabilization of ADA activity. This decline was mainly due to marked decrease(p<0.05) in ADA2. The ratio ( >0.75) of ADA(2)/ADA was found to be better indicator of tuberculosis. Lymphocyte neutrophil ratio (L/N) > 0.69 gave additional benefit to increase the sensitivity and specificity for the use of ADA as marker in diagnosing tuberculosis.

CONCLUSION

The combined use of activity of ADA, its isoenzymes and total and differential cell counts is a better indicator and gives better understanding to diagnose and evaluate tuberculosis and response to therapy.