Study objective: To delineate the course of serum adenosine deaminase (s-ADA) in patients with tuberculosis who are receiving effective therapy.
Setting: A medical ward and an outpatient clinic in a general hospital.
Patients: Twenty-five immunocompetent patients with pleural or pulmonary tuberculosis.
Interventions: All patients received standard chemotherapeutic regimens with isoniazid, rifampin, and pyrazinamide.
Measurements and results: Six measurements of several variables, including s-ADA, were carried out at different periods of time during the 6 months of follow-up. There were no significant differences in s-ADA values between sexes and there was no significant correlation with age or with the other variables analyzed. There was a significant decline in the s-ADA values during the first 2 months in the patients as a whole (p=0.04), followed by a stabilization of the s-ADA activity. This decline was due to a marked decrease in the s-ADA in the 13 patients (52%) who had initial high levels of the enzyme (p=0.03), whereas there were no changes in those patients with normal initial levels (p=0.27). Patients with increased s-ADA activity at the time of the first measurement reported symptoms for a longer period than patients with normal s-ADA (median, 15 vs 10 days; p=0.02).
Conclusions: s-ADA levels in patients with tuberculosis decrease during the initial months of effective treatment. Perhaps this decrease might reflect the normalization of the altered lymphocyte turnover induced by tuberculosis. The measurement of s-ADA could be of some help to evaluate the response to therapy, particularly in those patients with increased values of the enzyme.