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# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Sirolimus, Blood (SIIRO)
Test Code: SIROSO
Synonyms/Keywords
​Ref Lab Code: 81768, Rapamune, Rapamycin
Useful For
Monitoring whole blood sirolimus concentration during therapy, particularly in individuals coadministered CYP3A4 substrates, inhibitors, or inducers
 
Adjusting dose to optimize immunosuppression while minimizing toxicity
 
Evaluating patient compliance​
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Whole Blood​ EDTA ​EDTA Lavender Top Tube (LTT) ​3 mL ​1 mL
Collection Processing Instructions
1. Draw blood immediately before a scheduled dose.
2. Do not centrifuge.
3. Send specimen in original tube.
Additional Information:
1. Therapeutic range applies to trough specimen drawn immediately prior to a.m. dose.
2. For specimens sent ambient, sirolimus analysis cannot be performed; specimen must be sent refrigerated or frozen.
Specimen Stability Information
Specimen Type Temperature Time
​Whole Blood EDTA ​ ​ ​Refrigerated (preferred) ​7 days
​Frozen ​14 days
​Ambient ​48 hours
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Medical Laboratories Monday through Sunday​ ​Same day/1 day
High-Performance Liquid Chromatography/Tandem Mass Spectrometry (HPLC-MS/MS)​
Reference Lab
Test Information
​Trough sirolimus concentrations are generally measured every 5 days. Target concentrations vary depending on concomitant therapy, time posttransplant, the desired degree of immunosuppression, and adverse effects. When given with cyclosporine or tacrolimus, the therapeutic range for sirolimus is generally between 4 to 12 ng/mL, with minimal added benefit for concentrations >10 ng/mL. When sirolimus is given without calcineurin inhibitors, higher trough levels are needed; usually 12 to 20 ng/mL, but occasionally up to 20 to 30 ng/mL.
Reference Range Information
Performing Location Reference Range
​Mayo Medical Laboratories ​4-20 ng/mL
Interpretation
Most individuals display optimal response to sirolimus with trough whole blood levels 4 to 20 ng/mL. Preferred therapeutic ranges may vary by transplant type, protocol, and comedications.
 
Therapeutic ranges are based on specimens drawn at trough (ie, immediately before a scheduled dose). Blood drawn at other times will yield higher results.
 
The assay is specific for sirolimus; it does not cross-react with cyclosporine, cyclosporine metabolites, tacrolimus, tacrolimus metabolites, or sirolimus metabolites. Results by liquid chromatography with detection by liquid chromatography/tandem mass spectrometry are approximately 30% less than by immunoassay.
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​80195
Synonyms/Keywords
​Ref Lab Code: 81768, Rapamune, Rapamycin
Ordering Applications
Ordering Application Description
​Centricity ​Sirolimus, Blood (SIRO)
​Cerner ​Sirolimus, Blood, (SIRO)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Whole Blood​ EDTA ​EDTA Lavender Top Tube (LTT) ​3 mL ​1 mL
Collection Processing Instructions
1. Draw blood immediately before a scheduled dose.
2. Do not centrifuge.
3. Send specimen in original tube.
Additional Information:
1. Therapeutic range applies to trough specimen drawn immediately prior to a.m. dose.
2. For specimens sent ambient, sirolimus analysis cannot be performed; specimen must be sent refrigerated or frozen.
Specimen Stability Information
Specimen Type Temperature Time
​Whole Blood EDTA ​ ​ ​Refrigerated (preferred) ​7 days
​Frozen ​14 days
​Ambient ​48 hours
Useful For
Monitoring whole blood sirolimus concentration during therapy, particularly in individuals coadministered CYP3A4 substrates, inhibitors, or inducers
 
Adjusting dose to optimize immunosuppression while minimizing toxicity
 
Evaluating patient compliance​
Test Information
​Trough sirolimus concentrations are generally measured every 5 days. Target concentrations vary depending on concomitant therapy, time posttransplant, the desired degree of immunosuppression, and adverse effects. When given with cyclosporine or tacrolimus, the therapeutic range for sirolimus is generally between 4 to 12 ng/mL, with minimal added benefit for concentrations >10 ng/mL. When sirolimus is given without calcineurin inhibitors, higher trough levels are needed; usually 12 to 20 ng/mL, but occasionally up to 20 to 30 ng/mL.
Reference Range Information
Performing Location Reference Range
​Mayo Medical Laboratories ​4-20 ng/mL
Interpretation
Most individuals display optimal response to sirolimus with trough whole blood levels 4 to 20 ng/mL. Preferred therapeutic ranges may vary by transplant type, protocol, and comedications.
 
Therapeutic ranges are based on specimens drawn at trough (ie, immediately before a scheduled dose). Blood drawn at other times will yield higher results.
 
The assay is specific for sirolimus; it does not cross-react with cyclosporine, cyclosporine metabolites, tacrolimus, tacrolimus metabolites, or sirolimus metabolites. Results by liquid chromatography with detection by liquid chromatography/tandem mass spectrometry are approximately 30% less than by immunoassay.
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Medical Laboratories Monday through Sunday​ ​Same day/1 day
High-Performance Liquid Chromatography/Tandem Mass Spectrometry (HPLC-MS/MS)​
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​80195
For most current information refer to the Marshfield Laboratory online reference manual.