[The usefulness of adenosine deaminase determination in biological fluids for tuberculosis diagnosis]

Tuberculosis may affect several organs and its prevalence is continuously increasing. Laboratory diagnosis still remains difficult. Adenosine deaminase (Ada) is an enzyme which contributes to purine metabolism and its presence in lymphocyte, monocyte and macrophage cells is associated with T cells mediated immunity. Many studies have shown the usefulness of Ada determination in various biological fluids for the diagnosis of tuberculosis. In pleural fluid, cutoff vary from 33 to 48 U/L, with sensitivity higher than 80% and specificity near 100%. In peritoneal fluid the cutoff value is 30 U/L. In cerebrospinal fluid, the value of 7 U/L can make discriminate negative and positive cases with a good sensitivity and specificity. The data from the literature show that 50 U/L in pericardic fluid is a reliable threshold for tuberculosis diagnosis. Ada determination in serum is not as relevant as in others fluids because of its low specificity. Ada measurement in biological fluids, easy and not expensive, may be add to other biological tests for tuberculosis diagnosis.