Performance characteristics of a no-pretreatment, random access sirolimus assay for the Dimension RxL clinical chemistry system.
OBJECTIVE
Current therapeutic drug monitoring methods for sirolimus require a manual pre-treatment step and batch analysis. We describe and validate a no-pretreatment, random access sirolimus assay for the Dimension RxL clinical chemistry system from Siemens Healthcare Diagnostics Inc.


METHODS
Whole blood samples from renal transplant patients prescribed sirolimus were analyzed by the LC-MS/MS reference method, Abbott IMx and Dimension RxL methods in accordance with CLSI recommendations.


RESULTS
The Dimension sirolimus assay had a functional sensitivity of 2.0 ng/mL and repeatability and within-laboratory imprecision less than 12.6% at 3 ng/mL and less than 5% at 11-12 ng/mL. Least squares linear regression demonstrated the following relationships: RxL=1.20(LC-MS/MS) - 0.70, r=0.95 and RxL=1.33(IMx) - 0.75, r=0.96.


CONCLUSIONS
The Dimension sirolimus assay correlates well with the LC-MS/MS reference and IMx immunoassay methods and has the advantage of random access analysis without a manual pre-treatment step.
Cervinski
Mark A
MA
Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, Box 8118, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
Duh
Show-Hong
SH
Hock
Karl G
KG
Gray
Jeffery
J
Wei
Tie Q
TQ
Kilgore
Daniel C
DC
Christenson
Robert H
RH
Scott
Mitchell G
MG
D001681:Biological Assay / Q000379:methods* / Q000592:standards*; D002624:Chemistry, Clinical / Q000379:methods* / Q000592:standards*; D016903:Drug Monitoring / Q000379:methods* / Q000592:standards*; D006801:Humans; D020123:Sirolimus / Q000097:blood*
D020123:Sirolimus