This is a highly specialized test to find the cause of fluid buildup, particularly around the lungs (pleural fluid) or abdomen (ascitic fluid). It measures the level of Adenosine Deaminase (ADA), an enzyme that is significantly elevated in response to certain infections. This test is one of the most reliable and rapid methods to help your doctor diagnose or rule out tuberculosis (TB) in these specific areas, allowing for a fast and accurate diagnosis. A sample of the specific body fluid is required, providing the critical, direct evidence your doctor needs to get you on the right treatment.