Activity of adenosine deaminase in cerebrospinal fluid for the diagnosis and follow-up of tuberculous meningitis in adults.

We studied the activity of adenosine deaminase in the cerebrospinal fluid of 40 normal controls and 205 patients who were grouped according to disease (tuberculous, viral, and purulent meningitis; neoplasms; stroke; and miscellaneous). The mean enzyme value was clearly higher for the patients with tuberculous meningitis (15.7 +/- 4.3 U/liter) than for the other patients (1.4 +/- 1.5 U/liter). The sensitivity of the test for diagnosing tuberculous meningitis was 1 and specificity, 0.99. The enzyme activity, as well as progression of the disease, was studied in 32 patients with tuberculous meningitis. A significant rise in levels of enzyme was observed during the first 10 days of therapy, was followed by a gradual decline, and reached normal values after three to four months of treatment. Two patients showed substantial increases that coincided with the development of complications. The test proved to be a simple and reliable method for early diagnosis and follow-up of tuberculous meningitis.