Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Clinical utility
For therapeutic drug monitoring, sirolimus is measured in blood to establish optimal dosing, ensure compliance and prevent toxicity.
Clinical significance
Sirolimus is an mTOR inhibitor class of immunosuppressant drug used to prevent rejection after solid organ transplantation. Sirolimus has a different mechanism of action to ciclosporin and tacrolimus and therefore can be used in addition to ciclosporin and tacrolimus or as a substitute in patients intolerant to these drugs. An advantage of using sirolimus is the lack of nephrotoxicity, especially in renal transplant patients, allowing for a reduction in the dose of ciclosporin. Adverse effects of sirolimus are generally concentration-dependent, making therapeutic drug monitoring essential for monitoring whole blood concentrations during therapy (particularly in individuals co-administered therapeutic drugs), adjusting dose to optimise immunosuppression while minimizing toxicity, and evaluating patient compliance.
Specimen container paediatric:
Whole blood, Pink – EDTA
Specimen container adult:
Whole blood, Purple – EDTA
Minimum volume paediatric:
0.5 mL
Minimum volume adult:
0.5 mL
Special requirements:
A pre-dose (trough) sample is recommended
Sample stability:
Sirolimus is stable for at least 6 weeks when stored at 4°C prior to analysis. For long-term storage, samples should be frozen and stored at -20°C with stability of at least 6 months.
Transport requirements:
Ambient temperature
Freq Analysis:
Daily
Quality assurance:
UK NEQAS
Interpretation:
Target therapeutic ranges may vary depending on transplant type, length of time post-transplant and unit protocols, clinical indication, concomitant immunosuppression, and individual patient needs.
Reference ranges:
- Therapeutic range: 4 – 15 µg/L
- Potential toxicity: >25 µg/L
Factors affecting result:
Therapeutic ranges are based on trough levels, i.e. blood drawn immediately before a scheduled dose. Blood drawn at other times will yield higher results.
Other Info:
Whole blood sirolimus analysis is performed by LC-MS/MS.