Adenosine Deaminase (ADA) activity measured in Cerebrospinal Fluid (CSF-ADA) is a diagnostic marker primarily used to aid in the diagnosis of Tuberculous Meningitis (TBM).
Key Concepts
Enzyme and Function: ADA is an enzyme involved in purine catabolism. It is found in abundance in active T-lymphocytes and macrophages.
Mechanism in TBM: Increased ADA activity in CSF is an indicator of a vigorous cell-mediated immune response to the Mycobacterium tuberculosis bacteria in the central nervous system.
T-lymphocytes release ADA when stimulated by the mycobacterial antigens.
Clinical Utility: CSF-ADA estimation is valued for being a simple, inexpensive, and rapid test, especially crucial for early diagnosis in resource-limited settings where standard culture methods (which can be slow and have low yield) are difficult.