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Test ID TMP Trimethoprim, Serum


Specimen Required


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. Centrifuge and aliquot serum into plastic vial within 2 hours of collection.


Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.

Useful For

Monitoring trimethoprim therapy to ensure drug absorption, clearance, or compliance

Method Name

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

Reporting Name

Trimethoprim, S

Specimen Type

Serum Red

Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

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.

Reference Values

>2.0 mcg/mL (Peak)

Cautions

Specimens collected in serum gel tubes are not acceptable, as the drug can absorb on the gel and lead to falsely decreased concentrations.

Day(s) Performed

Monday, Thursday

Report Available

2 to 5 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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

NY State Approved

Yes