Adenosine Deaminase Activity in the Diagnosis of Tuberculous Meningitis and Its Levels in Other Diseases

Abstract

The diagnostic value of Adenosine Deaminase was studied to evaluate and establish a cut-off point for the diagnosis of tuberculous meningitis and also to establish its levels in other diseases in the local setting. There were 358 subjects in the study. The mean age of the adults was 29 ± 2; with a range of 13-74 years, while the age of the infants ranged from one day to 13 years. These were made up as follows: ‘Apparently healthy donors’ (30); tuberculous meningitis (230); pulmonary tuberculosis/pleural effusion (41); diabetics (15); Human Immunodefeciency Virus (22); hepatitis (10) and renal failure (10). The cut-off point was 9.0 IU/L with a sensitivity and specificity of 100% and 97% respectively for the diagnosis of tuberculous meningitis. The enzyme activity was compared with glycated haemoglobin in the long term monitoring of diabetics. The mean serum Adenosine Deaminase activity of healthy donors and Type II Diabetes Mellitus patients (before treatment) were 16.0 ± 1.0 and 38. 3 ±2.0 International Units/Litre respectively; (p < 0.001 versus healthy donors). After 8 weeks of treatment, the mean Adenosine Deaminase activity was reduced to 27.1 ±1 .6 IU/L significantly less than the initial value before treatment (p > 0.001). The mean Glycated Haemoglobin in healthy donors and Non-Insulin Dependent Diabetes Mellitus patients were 5.5% and 14.0% respectively (P < 0.001 versus healthy donors). With respect to the other diseases, the mean serum Adenosine Deaminase for hepatitis, renal failure, Human Immunodefeciency Virus and Acquired human Immunodeficiency Syndrome (tuberculosis positive patients) were 50 ± 2, 38 ± 1, 41 ± 1 and 64 ± 2 IU/L respectively. Pleural effusion Adenosine Deaminase level for pulmonary tuberculosis was 94 ± 1 IU/L. Even though Adenosine Deaminase activity is sensitive for the detection of tuberculosis it was not very specific. The specificity increases when interpreted together with clinical signs and other test results especially Cerebrospinal Fluid protein and cell count. Measurement of total Adenosine deaminase activity. Deaminase activity may also be an alternate important tool for monitoring Type II Diabetes Mellitus patients. In 22 patients who tested positive for the Human Immunodefeciency Virus the mean serum Adenosine Deaminase level in 10 tuberculosis positive patients was 75 ± 1 The remaining 12 all had full blown aids; ten of whom were TB positives with ADA level of 64 ± 2. While the remaining two were TB negative with ADA levels of 46 and 27 IU/L levels respectively. In liver disease 10 patients with acute hepatitis had a mean serum Adenosine Deaminase level of 50 ± 2 IU/L. There was no correlation between Adenosine Deaminase and Aspartate Aminotransferase but there was a moderate correlation (r = 0.5; p < 0.02) between Adenosine Deaminase and Alanine Aminotransferase. In renal disease 10 patient who had renal failure had a mean serum Adenosine Deaminase level of 38 ± 1 IU/L. There was no correlation between Adenosine Deaminase and any of the renal diagnostic parameters.