국내 임상검사실에서 질량분석법으로 시행하는 면역억제제 약물농도검사의 검사지침서 조사

초록

Background: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is preferable for quantifying immunosuppressants in whole blood because of its high accuracy and multiplexing capabilities. However, its implementation in clinical laboratories can be hindered by the complexity of method development and validation, particularly for practitioners with limited technical expertise. To facilitate broader adoption of LC-MS/MS- based testing, the Clinical Mass Spectrometry Committee of the Korean Society for Clinical Chemistry conducted a survey to collect and analyze standard operating procedures (SOPs) currently used for LC-MS/MS-based immunosuppressant assays. Methods: SOPs from seven institutions, each with independently developed and validated LC-MS/MS assays for immunosuppressants, were col- lected and analyzed. Key categories included sample handling, reagent preparation, sample pretreatment, and liquid chromatographic and mass spectrometry parameters. Results: Four institutions measured all four immunosuppressants (tacrolimus, cyclosporine A, sirolimus, everolimus), while others measured two or three. All laboratories used EDTA-anticoagulated whole blood and employed protein precipitation with ZnSO4 and organic solvents. Re- versed-phase chromatography using a C18 column with gradient elution was most commonly used. All institutions used commercial calibrators and quality controls. Internal standards varied, but cyclosporine D and ascomycin were most frequently used. While LC-MS/MS instruments and analytical conditions varied, all institutions employed electrospray ionization and monitored ammonium adducts in multiple reaction monitoring. Conclusions: These findings provide a comprehensive summary of current LC-MS/MS practices for immunosuppressant monitoring and may serve as a practical reference for laboratories to implement or optimize LC-MS/MS-based immunosuppressant assays.

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