✍️ Written by the MedTestBD Editorial Team · Last reviewed: July 2026
What is the Adenosine Deaminase (ADA) Test?
The Adenosine Deaminase (ADA) test measures the level of ADA enzyme in body fluids — most commonly pleural fluid (around the lungs), ascitic fluid (in the abdomen), or cerebrospinal fluid (around the brain). ADA is produced by activated T-lymphocytes — immune cells that respond strongly to tuberculosis (TB). Elevated ADA levels in fluid samples are one of the most reliable indicators of TB infection at those sites, making it a critical test in Bangladesh where TB remains highly prevalent.
Why is the ADA Test Done?
- To diagnose tuberculous pleural effusion — fluid around the lungs caused by TB
- To investigate tuberculous peritonitis — TB infection causing fluid accumulation in the abdomen
- To support the diagnosis of tuberculous meningitis — TB affecting the brain's lining
- To differentiate TB from other causes of fluid accumulation such as cancer or heart failure
- When sputum tests or culture results are unavailable, delayed, or negative despite clinical suspicion of TB
Normal ADA Levels
| Sample Type | Normal ADA Level | TB-Suggestive Threshold |
|---|---|---|
| Pleural fluid | Below 40 U/L | Above 40 U/L — strongly suggests TB pleuritis |
| Ascitic fluid | Below 33 U/L | Above 33–39 U/L — suggests TB peritonitis |
| CSF (meningitis) | Below 10 U/L | Above 10 U/L — supports TB meningitis |
| Serum (blood) | 5 – 25 U/L | Elevated in active TB and some autoimmune conditions |
ADA has high sensitivity and specificity for TB in pleural fluid — a level above 40 U/L in pleural fluid is considered diagnostic of TB pleuritis in the right clinical context. However, ADA can also be elevated in lymphoma and empyema, so results must be interpreted alongside clinical findings, imaging, and other TB tests.
How to Prepare for the ADA Test
- No fasting is required for a blood ADA test
- For fluid samples (pleural, ascitic, or CSF), the sample is collected by a doctor through a needle procedure — the preparation and fasting instructions are determined by the doctor based on the procedure type
- Inform your doctor about any TB medications you are already taking, as treatment reduces ADA levels
- Bring previous chest X-rays, CT scan reports, or TB test results for the doctor's reference
ADA Test Price in Bangladesh
ADA test prices vary between diagnostic centers across Bangladesh. Compare ADA test prices on MedTestBD →
⚠️ This information is for general reference only. Always consult a qualified physician before undergoing any medical test.
