Measurement of Adenosine Deaminase Activity in Urine with LCMS-8040

Significance of the Topic

Adenosine deaminase (ADA) catalyzes deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively,
and its activity in biological fluids reflects immune function and purine metabolism.
Accurate measurement of ADA in urine supports monitoring of immunodeficiencies such as SCID and other metabolic disorders.

Objectives and Study Overview

The study aimed to establish a rapid, sensitive LC–MS/MS method on the Shimadzu LCMS-8040 platform to quantify ADA activity by measuring substrates and products in urine.
The protocol, developed at the Meyer Children's Hospital, was extended to plasma and dried blood spots (DBS) for comparative preparation workflows.

Methodology and Sample Preparation

Samples included urine, plasma, and DBS, extracted with methanol and water, spiked with 13C-labeled internal standards for adenosine and deoxyadenosine.
Enzymatic reaction was performed at 37 °C for 25 minutes to convert substrates before LC–MS/MS analysis.

Used Instrumentation

• Shimadzu LCMS-8040 triple quadrupole mass spectrometer with ESI(+) source
• Synergi Fusion RP column (150 mm × 2 mm I.D., 4 μm)
• Mobile phase: 0.1% formic acid in water (A) and acetonitrile (B), isocratic 60% B
• Flow rate: 0.2 mL/min, column temperature: 30 °C, injection: 3 μL, analysis time: 5 min
• MRM transitions: ADO m/z 267.8>136.05, dADO 251.8>136.05, IS transitions accordingly

Main Results and Discussion

Extracted-ion chromatograms demonstrated a clear peak for deoxyadenosine in samples containing ADA activity, while control samples showed no signal.
The method provided high sensitivity and selectivity in a short runtime, confirming its suitability for detecting ADA-driven substrate conversion.

Benefits and Practical Applications

• Rapid analysis with a 5 min cycle time enables high throughput
• Applicable to multiple matrices including urine, plasma, and DBS
• Quantitative internal standard calibration ensures robust results
• Suitable for research in immunodeficiency screening and purine metabolism studies

Future Trends and Prospects

Integration with newborn screening platforms and automation could expand clinical utility.
Adaptation to detect other enzymopathies and incorporation into comprehensive metabolic panels are potential developments.

Conclusion

The described LC–MS/MS approach delivers a reliable and efficient protocol for measuring ADA activity in urine and other matrices, supporting both research and potential clinical applications with high sensitivity and throughput.

References

• La Marca G et al. J Pharm Biomed Anal. 2014;88:201–206
• La Marca G et al. J Allergy Clin Immunol. 2013;131(6):1604–1610