ADA is the abbreviation of Adenosine Deaminase, It’s a protein produced by cells all over the body. Due to infections, especially like infections by mycobacterium tuberculosis. Elevated amount of ADA produced in the places (Eg. Pleural fluid) where bacteria are present. Increased serum ADA has been observed in cases like acute hepatitis, alcoholic hepatic fibrosis, liver cirrhosis etc. This test can be performed in serum, plasma, pericardial fluid, Pleural fluid, ascitic fluid and CSF