Specimen Requirements Specimen Whole blood Volume 3 mL Minimum Volume 1.1 mL Container Lavender-top (EDTA) tube Collection Trough: 30 minutes to one hour before the next oral dose Storage Instructions Room temperature Stability Requirements Temperature Period Room temperature 14 days Refrigerated 14 days Frozen 14 days Freeze/thaw cycles Stable x3 Patient Preparation Trough levels are most reproducible. Causes for Rejection Clotted specimen Test Details Use Monitor immunosuppressive therapy following organ transplant Limitations This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration. Methodology Liquid chromatography/tandem mass spectrometry (LC/MS-MS) Reference Interval 3.0−20.0 ng/mL Additional Information Sirolimus may be administered in conjunction with cyclosporine (CsA) and corticosteroids to reduce or prevent host graft rejection. Using this therapy, peak concentrations are achieved in one to two hours. The mean terminal elimination half-life is 62 hours.1 Drug-drug interactions, including CsA, may alter the pharmacokinetics of sirolimus, making therapeutic drug monitoring appropriate.