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Test Code Billings Clinic: 9088 Mayo: SIIRO Sirolimus, Whole Blood

Reporting Name

Sirolimus, B

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Monitoring whole blood sirolimus concentration during therapy, particularly in individuals coadministered cytochrome P450 (CYP) 3A4 substrates, inhibitors, or inducers

 

Adjusting dose to optimize immunosuppression while minimizing toxicity

 

Evaluating patient compliance

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)


Specimen Required


Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions:

1. Draw blood immediately before a scheduled dose.

2. Do not centrifuge.

3. Send whole blood specimen in original tube. Do not aliquot.

Additional Information: Therapeutic range applies to trough specimen collected immediately prior to a.m. dose.


Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK
Clotted specimens Reject

Reference Values

4-20 ng/mL (Trough)

 

Target steady-state trough concentrations vary depending on the type of transplant, concomitant immunosuppression, clinical/institutional protocols, and time post-transplant. Results should be interpreted in conjunction with this clinical information and any physical signs/symptoms of rejection/toxicity.

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 collected at trough (ie, immediately before a scheduled dose). Higher results will be obtained when the blood is collected at other times.

 

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 tandem mass spectrometry are approximately 30% less than by immunoassay.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 3 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80195

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SIIRO Sirolimus, B 29247-4

 

Result ID Test Result Name Result LOINC Value
35144 Sirolimus, B 29247-4

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Renal Diagnostics Test Request (T830)

-Therapeutics Test Request (T831)