Adenosine Deaminase (ADA), Fluid

What it is:
This test measures the level of adenosine deaminase (ADA), an enzyme involved in purine metabolism, in body fluids (commonly pleural fluid from around the lungs). Elevated ADA activity is linked with certain infections and immune responses.

Uses

• Aid in the diagnosis of tuberculosis (TB) pleuritis

• Distinguish between tuberculous pleural effusion and effusions caused by other conditions

• Evaluate unexplained fluid accumulation in pleural, peritoneal, or cerebrospinal fluid (CSF)

Symptoms That May Lead to the Test

• Persistent cough and chest pain

• Shortness of breath

• Fever, night sweats

• Unexplained weight loss

• Fluid buildup seen on imaging (pleural effusion, ascites, etc.)

Abnormal Results

• High ADA levels:

  • Strongly suggest tuberculosis-related pleural effusion

  • May also be seen in other infections, some lymphomas, and autoimmune diseases

• Low or normal ADA levels:

  • Less likely to indicate tuberculosis

  • May point toward non-TB causes of fluid accumulation (e.g., heart failure, malignancy not related to TB)

Risks

• Risks depend on the fluid collection procedure (e.g., thoracentesis, lumbar puncture):

  • Mild pain, bruising, or bleeding at puncture site

  • Rarely infection or injury to nearby structures