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HelpTest Code TMP Trimethoprim, Serum
Reporting Name
Trimethoprim, SUseful For
Monitoring trimethoprim therapy to ensure drug absorption, clearance, or compliance
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Serum RedSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top (gel tubes/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Serum for a peak level should be collected at least 60 minutes after a dose.
2. Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum Red | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reference Values
>2.0 mcg/mL (Peak)
Day(s) Performed
Monday, Thursday
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
80299
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| TMP | Trimethoprim, S | 11005-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 80146 | Trimethoprim, S | 11005-6 |
Clinical Information
Trimethoprim is coadministered with sulfamethoxazole for prophylaxis or treatment of bacterial infections. These agents are used to treat a variety of infections, including methicillin-resistant Staphylococcus aureus, and for prophylaxis in immunosuppressed patients, such as individuals who are HIV-positive.
Trimethoprim has a wide therapeutic index and dose-dependent toxicity. Trimethoprim accumulates in patients with kidney failure.
Therapeutic drug monitoring is not commonly performed unless there are concerns about adequate absorption, clearance, or compliance. Accordingly, routine drug monitoring is not indicated in all patients.
Interpretation
Most patients will display peak steady state serum concentrations of more than 2.0 mcg/mL when the specimen is collected at least 1 hour after an oral dose. Target concentrations may be higher depending on the intent of therapy.
Clinical Reference
1. Kamme C, Melander A, Nilsson NI. Serum and saliva concentrations of sulfamethoxazole and trimethoprim in adults in children: Relation between saliva concentrations and in vitro activity against nasopharyngeal pathogens. Scand J Infect Dis. 1983;15(1):107-113. doi:10.3109/inf.1983.15.issue-1.18
2. Young T, Oliphant C, Araoyinbo I, Volmink J. Co-trimoxazole prophylaxis in HIV: the evidence. S Afr Med J. 2008;98(4):258-259
3. Avdic E, Cosgrove SE. Management and control strategies for community-associated methicillin-resistant Staphylococcus aureus. Expert Opin Pharmacother. 2008;9(9):1463-1479. doi:10.1517/14656566.9.9.1463
4. Brunton LL, Hilal-Dandan R, Knollmann BC, eds. Goodman and Gilman's: The Pharmacological Basis of Therapeutics. 13th ed. McGraw-Hill Publishing; 2018
Method Description
Samples are extracted with analyte detection by tandem mass spectrometry.(Unpublished Mayo method)
Report Available
2 to 5 daysSpecimen Retention Time
14 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
Cautions
Specimens collected in serum gel tubes are not acceptable, as the drug can absorb on the gel and lead to falsely decreased concentrations.
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.