Dried blood spot analysis of creatinine with LC-MS/MS in addition to immunosuppressants analysis
- 783 Downloads
In order to monitor creatinine levels or to adjust the dosage of renally excreted or nephrotoxic drugs, the analysis of creatinine in dried blood spots (DBS) could be a useful addition to DBS analysis. We developed a LC-MS/MS method for the analysis of creatinine in the same DBS extract that was used for the analysis of tacrolimus, sirolimus, everolimus, and cyclosporine A in transplant patients with the use of Whatman FTA DMPK-C cards. The method was validated using three different strategies: a seven-point calibration curve using the intercept of the calibration to correct for the natural presence of creatinine in reference samples, a one-point calibration curve at an extremely high concentration in order to diminish the contribution of the natural presence of creatinine, and the use of creatinine-[2H3] with an eight-point calibration curve. The validated range for creatinine was 120 to 480 μmol/L (seven-point calibration curve), 116 to 7000 μmol/L (1-point calibration curve), and 1.00 to 400.0 μmol/L for creatinine-[2H3] (eight-point calibration curve). The precision and accuracy results for all three validations showed a maximum CV of 14.0 % and a maximum bias of −5.9 %. Creatinine in DBS was found stable at ambient temperature and 32 °C for 1 week and at −20 °C for 29 weeks. Good correlations were observed between patient DBS samples and routine enzymatic plasma analysis and showed the capability of the DBS method to be used as an alternative for creatinine plasma measurement.
KeywordsDried blood spot Creatinine Tacrolimus Sirolimus Everolimus Cyclosporin A
Conflict of interest
The authors declare no conflicts of interest.
- 8.Koster RA, Alffenaar JWC, Botma R, Greijdanus B, Touw DJ, Uges DRA, Kosterink JGW (2015 In Press) What is the right blood hematocrit preparation procedure for standards and quality control samples for dried blood spot analysis? BioanalysisGoogle Scholar
- 10.Food and Drug Administration, U.S. Department of Health and Human Services (2001) Guidance for Industry, Bioanalytical Method ValidationGoogle Scholar
- 14.Boyanton BL Jr, Blick KE (2002) Stability studies of twenty-four analytes in human plasma and serum. Clin Chem 48:2242Google Scholar
- 15.O’Keane MP, Cunningham SK (2006) Evaluation of three different specimen types (serum, plasma lithium heparin and serum gel separator) for analysis of certain analytes: clinical significance of differences in results and efficiency in use. Clin Chem Lab Med 44:662Google Scholar
- 16.Cannan RK, Shore A (1928) The creatine-creatinine equilibrium. The apparent dissociation constants of creatine and creatinine. Biochem J 22:920Google Scholar
- 18.Wyss M, Kaddurah-Daouk R (2000) Creatine and creatinine metabolism. Physiol Rev 80:1107Google Scholar