Overview: Adenosine Deaminase TestIntroduction: The Adenosine Deaminase Test measures an enzyme to diagnose tuberculosis, which may cause cough, fever, or weight loss, particularly in the lungs or other organs. Following 2023 WHO guidelines, it uses an immunoassay for high sensitivity, aiding in confirming infectious diseases. This test is critical for guiding antitubercular therapy, preventing disease spread, and improving outcomes in infectious disease management.
Other Names: ADA Test, Adenosine Deaminase Assay.
FDA Status: Laboratory-developed test (LDT), meeting immunology standards for diagnostic accuracy.
Historical Milestone: ADA was linked to tuberculosis in the 1970s. Immunoassays emerged in the 1980s, and by the 2000s, improved assays enhanced diagnostic specificity.
Purpose: Diagnoses tuberculosis, guides therapy, and monitors disease in patients with cough, fever, or weight loss.
Test Parameters: 1. Adenosine Deaminase
Pretest Condition: No fasting required. Collect serum, plasma, CSF, or pleural fluid at symptom onset. Report respiratory symptoms or tuberculosis exposure.
Specimen: 2-5 mL serum (SST), 2-4 mL plasma (EDTA), 1-2 mL CSF, or 5-10 mL pleural fluid (sterile container). Transport in a biohazard bag within 8 hours.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 7 days
Sample Stability at Frozen: 6 months
Medical History: Document cough, fever, weight loss, or family history of tuberculosis. Include current medications or recent infections.
Consent: Written consent required, explaining the test's purpose, diagnostic implications, and potential therapy needs.
Procedural Considerations: Uses an immunoassay to measure ADA levels. Results are available in 1-2 days, supporting rapid diagnosis.
Factors Affecting Result Accuracy: Non-tuberculous infections may elevate ADA levels, causing false positives. Improper storage can degrade samples.
Clinical Significance: Elevated ADA levels suggest tuberculosis, prompting therapy. Normal levels may require culture or PCR to rule out infection.
Specialist Consultation: Consult an infectious disease specialist for result interpretation. Pulmonology referral is advised for lung involvement.
Additional Supporting Tests: TB culture, GeneXpert MTB/RIF, or chest X-ray to confirm tuberculosis diagnosis.
Test Limitations: Non-specific ADA elevation requires clinical correlation. False negatives may occur in early disease.
References: WHO Tuberculosis Guidelines, 2023; Lewinsohn DM, Clinical Infectious Diseases, 2022.
