Combined Measurement of Immunosuppressive Agents, Creatinine and Hematocrit in a Single Dried Blood Spot Using LC-MSMS and Near-infra-Red Spectrometry

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A.C. Egas, M.J.C. Wessels-Bakker, J.M. Kwakkel-van Erp, M.E. Janssen, B. Luijk, E.A. van de Graaf, M. Oostendorp, El Amrani, E.M. van Maarseveen

Chair(s): dr. M.H.L. Christiaans & dr. R.J. Toorop

Thursday 9 march 2017

8:36 - 8:48h at Johan de Meesterzaal

Categories: Parallel - Klinisch

Parallel session: Parallelsessie XI – Klinisch 3 - Early Bird sessie 2

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Purpose:
Biomarker and drug monitoring and are essential to diagnose and prevent toxicity and rejection in lung transplant recipients. To date, whole blood sampling is ‘the golden standard’ for quantification of drugs and biomarker in either whole blood of serum. Nevertheless, whole blood sampling in stable transplant recipients usually takes place at the outpatient clinic and is rarely carried out by patients themselves at home. Therefore, we have developed a practical method for rapid and easy quantification of hematocrit (Ht), creatinine (Creat) and immunosuppressive agents (IMx) in dried blood spot (DBS) samples.

Methods:
For Ht measurement near-infrared (NIR) spectrometry combined with an in-house developed NIR-model and Büchi NIRcal 5.5 software  were used to nondestructively quantitate Ht in DBS. Thereafter, DBS samples were extracted under ultrasonication for 15 minutes. IMx and Creat  were detected with a Thermo Scientific triple quadrupole Quantum Access with positive ionization. Following analytical validation methods were clinically validated by comparing DBS results with whole blood and serum reference methods. Venous whole blood samples of 30 patients on cyclosporin A, tacrolimus, sirolimus and everolimus were used to prepare DBS. Ht, IMx and Creat concentrations determined by DBS and whole blood or serum methods were compared by Passing & Bablok regression analysis.

Results:
A good correlation was demonstrated yielding linear regression coefficients of R2 >0.95. for all compounds and Ht. Low, medium and high controls are all <15% in all cases. The average concentrations of Ht, IMx and Creat in the population were within the 95% limits of agreement.

Conclusion:
A rapid and combined dried blood spot analysis suitable for patient home monitoring of immunosuppressants, creatinine and hematocrit in lung transplant recipients using a single sample was successfully developed.